3

The Effects of Summertime Experiences on Children’s Development

While children and youth have a variety of experiences during the summertime, there is evidence that access to high-quality experiences may not be equitable across different groups of children and youth, and this may have disparate effects on their development. In this chapter, we review what is known about how summer affects the development of children and youth across the four domains in the committee’s charge (see Box 3-1): (1) safety, risk-taking, and anti- and pro-social behavior, (2) physical and mental health and health-promoting behaviors, (3) social and emotional development, and (4) academic learning and opportunities for enrichment. We address them in this order to reflect the fundamental need for safety and health as a precursor for social and emotional development and academic learning. The chapter begins with a brief description of the developmental needs and stages of children and youth. Next, it examines what is known about how summer influences this development and the seasonal patterns observed within each domain. The extent to which summer programs and camps have been found to influence outcomes in each of the four domains, as well as the programmatic factors that enhance program effectiveness, is discussed in Chapter 4.

DEVELOPMENTAL NEEDS OF CHILDREN AND YOUTH

Before examining how summer affects their development, it is worth considering children’s and youth’s basic developmental needs, those that must be met in order for them to thrive. Maslow (1943) identified a basic set of needs: physiological (e.g., to satisfy hunger), followed by safety, and then by love/belonging (Maslow, 1943; see Figure 3-1). Each set of needs is conditioned upon meeting the ones before it, and motivation to meet these needs helps shape human behavior. If the more basic needs such as physiological ones are not met, a person cannot focus on higher-level needs, such as self-actualization. Once each set of needs is met, “other (and higher) needs emerge (p. 375).”

We know that children need adequate nutrition and safety for health and social/emotional stimulation to support psychological and cognitive development (Hoynes et al., 2016; Malin et al., 2018). Basic needs for food and safety are year-round needs and, of course, do not pause during the summer.

Research also shows that settings are critical to the development of physical, intellectual, psychological, social, and emotional skills and competencies (i.e., internal assets). In 2002, a National Research Council committee identified eight features of settings that support positive youth development (see Box 3-2). That committee highlighted that “exposure to positive experiences, settings, and people, as well as opportunities to gain and refine life

skills, supports young people in the acquisition and growth of [their] assets” (National Research Council and Institute of Medicine, 2002, p. 7).

Optimal implementation of the features of settings that promote positive development will vary across different types of settings (e.g., home vs. summer camps) and for youth of different ages (e.g., elementary vs. high school age students) and backgrounds. For example, appropriate structure for elementary school students will include greater adult oversight and supervision than for high school age youth. With this in mind, we provide a brief overview of the major developmental needs of youth across different age ranges. Because the committee’s statement of task focused on children and youth from the summer prior to kindergarten through grade 12, we focus our overview on these age groups.

DEVELOPMENTAL STAGES OF SCHOOL-AGE CHILDREN AND YOUTH

Physical, neurological, cognitive, and social and emotional changes occur within each child across time. Thus, what is both engaging and developmentally matched to the needs of a child at early elementary school age will differ from what engages and is developmentally appropriate for a child in later childhood and in different phases of adolescence. This is important, because when a youth’s environment is mismatched with his or her developmental needs it will not be able to optimally support youth outcomes (Eccles et al., 1993).¹ To promote thriving, developmental assets

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¹ A comprehensive view of the specific developmental needs of children and youth in different domains across time is beyond the scope of this report but has been addressed by previous National Academies’ reports (e.g., Institute of Medicine, 2000; National Academies of Sciences, Engineering, and Medicine, 2019a).

should be aligned with youth’s specific needs in each stage of their development. Importantly, skill development is not linear. Rather, it is extremely malleable and dependent on context, and it demonstrates both within- and between-youth variability (Cantor et al., 2018). How skills develop within particular contexts will depend on both individual susceptibility to environmental influences and the timing of different periods of brain development. Further, children come into settings with existing skills, competencies, and experiences that they can draw on to promote further development (Ambrose and Lovett, 2014; Deans for Impact, 2015).

Early, Middle, and Late Childhood

Child development during the preschool years is foundational in shaping the assets children will bring with them at the launch of their formal schooling. Understanding early childhood development is therefore essential to interpretating the trajectory of child development in the school years and beyond. The brain is continually changing as children experience new settings and interactions within settings (Baltes et al., 2006). The ages of 0–3 are a sensitive period of rapid brain growth and development of emotions, language, cognition, and motor control (Center on the Developing Child, 2016; Johnson et al., 2016; Tarullo et al., 2009). Experiences during this time set the stage for later development. In particular, increasing evidence has cited the importance of high-quality childcare and early education for fostering healthy development in early childhood and mitigating disparities in a range of outcomes that are present at school entry (Institute of Medicine, 2000; National Academies of Sciences, Engineering, and Medicine, 2019a). This evidence suggests there is also more to be learned about the importance of supportive settings for developmental outcomes in later childhood and adolescence, as well.²

In early childhood, children are learning to regulate their emotions and social relationships and to integrate their emotions, cognition, and behaviors (Espinet et al., 2012). Learning to identify and regulate emotions as well as direct attention are important tasks during this period (National Commission on Social, Emotional, and Academic Development, 2019) and children are still developing these skills when they enter school. Both executive function and theory of mind (defined below) develop during early childhood through a combination of cognitive, neural, and social developmental processes. Executive function comprises a variety of important and

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² For information on early childhood development (from birth to pre–K), the committee refers readers to prior National Academies reports, including From Neurons to Neighborhoods: The Science of Early Childhood Development (2000); Transforming the Workforce for Children Birth through Age 8: A Unifying Foundation (2015); A Roadmap to Reducing Childhood Poverty (2019); and Vibrant and Healthy Kids: Aligning Science, Practice, and Policy to Advance Health Equity (2019).

complex skills that include the ability to regulate attention and cognition and to plan, sequence, adjust, and organize behavior (Institute of Medicine, 2000). Theory of mind is the child’s understanding of themselves and others as having their own beliefs, motivations, and feelings (Astington and Edward, 2010; Wellman, 2014). The development of these regulatory processes in early childhood is “deeply embedded in the child’s relations with others” (Institute of Medicine, 2000, p. 122). The processes of self-regulation and executive function processes continue to undergo rapid development during middle childhood (Johnson et al., 2016). Children at all ages learn by exploring the world, and in a culturally situated manner they learn through scaffolding from adults and older peers (Rogoff, 2003; Vygotsky, 1978). Indeed, nurturing relationships are critical to healthy child development (Britto et al., 2017).

During early childhood, children are extremely sensitive to environmental influences. Thus, how they experience the school transition may influence their adjustment in ways that have long-term impacts on their developmental trajectories, and the transition can be made more difficult by social structural factors such as poverty, weak family structure, and a lack of available preschool (Entwisle and Alexander, 1998).

Chronic stress has significant, negative consequences for brain development (Center on the Developing Child, 2016; Essex et al., 2011; Teicher et al., 2016). These effects can be compounded by environments that are not developmentally supportive (Osher et al., 2018). Cumulative effects of chronic stress can also impact later development (Blair and Diamond, 2008; Portilla et al., 2014). Indeed, adverse childhood experiences (ACES) have been linked to negative childhood educational outcomes (e.g., Blodgett and Lanigan, 2018) as well as later health and well-being outcomes, including mortality (e.g., Felitti et al., 2019). Yet these cumulative effects can also be mitigated when buffered by supportive environments (Fischer and Bidell, 2006), making it all the more critical to consider ways that summertime presents unique opportunities for providing developmentally promotive relationships and contexts for all children and youth.

Participation in structured activities is important; a child’s participation in structured activities has been linked to cognitive and emotional development (Hofferth and Sandberg, 2001) as well as positive functioning in the areas of academic performance, psychological health, and behavior (Bartko and Eccles, 2003). While participation in structured activities is important for youth outcomes, research also suggests that, in fact, youth need a balance of structured and unstructured activities for optimal development. For instance, Mahoney and Stattin (2000) found that a lack of participation in unstructured activities was associated with anti-social behavior and that participation in structured activities was associated with pro-social behavior. Play, which is often unstructured, is critical to children’s development and can promote

decision making, social skills, and creativity (Ginsburg, 2007). Play is an important tool for elementary-age children, both to engage them in academic learning and to foster growth and a sense of competency in a variety of developmental domains (Ginsburg, 2007; Milteer et al., 2012). Play promotes development in a number of areas, including cognitive, social emotional, and physical, and when engaged in with parents or other adults, play also promotes the development of supportive relationships (Yogman et al., 2018).

Out-of-school and summer programs can play a variety of important roles in supporting healthy development during childhood. First, out-of-school and summer programs provide a setting for children to experience supportive social relationships with both adults and peers, relationships that foster emotional, behavioral, and cognitive development. Second, such programs offer an opportunity for both structured and unstructured play, as well as a child’s choice in activities. This may be particularly important as schools increasingly focus on structured academic learning, even in the early grades (Bassok et al., 2016), and as other societal changes, such as increased parental employment and greater digital engagement decrease opportunities for unstructured play (Yogman et al., 2018). Third, some programs offer specific support for children with a history of adverse childhood experiences and trauma.

Early Adolescence

Overall, the brain demonstrates great plasticity during adolescence, a time when “learning and development are inextricably intertwined” (Harper et al., 2018a, p. 6) and when the settings with which youth engage can provide developmentally supportive opportunities. Whereas we often frame the adolescent brain as “in development” or as a less mature version of the adult brain, it is important to realize that the adolescent brain is particularly well suited for achieving the developmental tasks associated with this period of development, when young people are transitioning from childhood to adulthood, gaining autonomy, and figuring out who they will be in the adult world (National Academies of Sciences, Engineering, and Medicine, 2019a). At the same time, early adolescents are susceptible to a number of mental and physical health risks (Harper et al., 2018a), which can affect their learning and development if they are not provided with appropriate supports, such as those from adults and developmentally aligned settings. The effects of stress, for example, are particularly pronounced during adolescence, and inequities associated with economic disadvantage, racism, and other types of structural discrimination all can harm the development of adolescents (Harper et al., 2018c).

Whereas we think of adolescence as a time when youth begin to gravitate away from adults and toward peers, and peers do indeed take on

increasing importance during adolescence, adult support is still critical for young people during this period. Adolescents are “especially sensitive to the attitudes and behaviors of adult members of the community” (National Academies of Sciences, Engineering, and Medicine, 2019a, p. 5). Further, while adolescents experience increasing independence and desire more autonomy than children, they also report that the demands of this independence can be stressful, particularly when they do not feel they have needed supports (National Academies of Sciences, Engineering, and Medicine, 2019a). Thus, both parents and other caring adults, such as natural mentors (supportive adults who occur naturally in a youth’s social network) are important sources of support that promote positive development and resiliency for adolescents (National Academies of Sciences, Engineering, and Medicine, 2019a).

During early adolescence, physiological, neurological, and contextual changes occur simultaneously (Nelson et al., 2005; Sisk and Zehr, 2005), leading to a period of great opportunity for brain malleability. This period results in greater capacities for conceptual thinking, regulation, and judgment (Siegel, 2013). It also includes greater tendencies toward risk-taking, both positive and negative, and greater impulsivity through shifts in the brain’s dopamine-linked reward system (Osher et al., 2018; Siegel, 2013). When children enter adolescence, they become increasingly sensitive to social cues and to social recognition and rewards (Harper et al., 2018b). This can lead to impulsive decision making in certain situations, particularly in the presence of peers, to whose influence adolescents can be susceptible (National Academies of Sciences, Engineering, and Medicine, 2019a). The increased sensitivity to peer influence and social belonging during this period means that adolescents are open to both positive and negative peer pressure, making opportunities to engage in positive activities with pro-social peers all the more important. At the same time, programs that engage youth who are at risk for or already engaging in risky or anti-social behaviors are vulnerable to contagion effects through deviancy training³ or other processes of negative peer influence (Dishion and Tipsord, 2011). Negative peer influence can be minimized in both structured (i.e., programs) and unstructured (i.e., natural) settings through the presence of supportive adults and positive parenting (Dishion and Tipsord, 2011).

The transition from elementary school to middle school during this period has also been associated with decreased academic achieve-

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³ Deviancy training “involves the interpersonal dynamic of mutual influence during which youth respond positively to deviant talk and behavior . . . the deviancy training process is characterized by give-and-take exchanges between friends that promote deviant actions (e.g., past stories of deviant acts, suggestions for future behavior, what ifs) and elicit positive responses, such as laughter” (Dishion and Tipsord, 2011).

ment (Kurtz-Costes and Rowley, 2012; Ryan et al., 2013) and declines in self-esteem and self-worth (Ryan et al., 2013; Wigfield et al., 1991). Declines in the intrinsic value of schoolwork and achievement goals within the last year of elementary school also suggest a possible developmental trajectory during early adolescence that is not solely dependent on the school transition (Ryan et al., 2013; Shim et al., 2008).

Research on youth in out-of-school programs during early adolescence contributes to our understanding of how summer programming may support youth during this developmental period. One randomized controlled study of afterschool programs for middle school students at five underperforming schools found that unsupervised socializing was associated with increased drug use and delinquency (Cross et al., 2009). Yet the afterschool program itself showed only small effects on these risk-taking and anti-social behaviors. Although afterschool and summer programs have the potential to fill otherwise unsupervised time, it appears that the programs in this study were not attracting students who would otherwise be unsupervised and therefore be at higher risk for delinquency. Further, attendance was highly variable. The authors conclude that chool programs need to more intentionally create programs for and recruit those youth who are at highest risk of unsupervised socializing.

Related to the last finding, research on a representative sample of middle schoolers in Sweden found that participation in highly structured programs was associated with lower levels of anti-social behavior. It also found, that youth participants in programs with little structure tended to have peers who were older, had lower academic achievement, and a record of engaging in more delinquent behaviors (Mahoney and Stattin, 2000). Further, for youth at risk of delinquency and anti-social behavior, a longitudinal study of youth from five communities in the southeastern United States found that participation along with their friends in extracurricular activities was a protective factor, meaning that those youth who joined extracurricular activities were less likely than their peers to drop out of school or be arrested (Mahoney, 2000). In a study of a diverse group of fifth graders from 13 states (Lerner et al., 2005), researchers verified the relationship between five youth factors—Confidence, Competence, Character, Caring, and Connection (i.e., the “5 C’s”)—and the construct of Positive Youth Development (PYD), a term frequently used in the youth development field but previously unsubstantiated empirically. These 5 C’s were found to produce a sixth C: youth Contribution to self, family, community, and society. Among these early adolescents, the study found that participation in youth development programs was associated with higher levels of PYD and Contribution.

Youth development programs, including summer programs, may have both promotive and preventative effects for early adolescents, but the

recruitment of and attendance or participation by those youth who may be in greatest need of supportive and structured environments are key. At the same time, programs must be cognizant of potential contagion effects when serving youth who are engaging in or at risk of engaging in behaviors that are risk-taking (e.g., substance use, unprotected sexual activity) and anti-social (e.g., aggression, delinquency). Programs can guard against such effects by ensuring appropriate levels of structure and adult monitoring and support (Dishion and Tipsord, 2011).

Middle to Late Adolescence

In middle and later adolescence, the rapid changes that have been occurring in the youth’s physiological, neurological, biological, and emotional systems are coming into balance. During these years, adolescents are concerned with exploring and forming a coherent sense of their own identities and thinking about their values, beliefs, and purpose in life, and they tend to demonstrate more goal-directed behavior and a desire for increased autonomy (Nagaoka et al., 2015). Cognitive advances mean that across middle and late adolescence youth are more able to integrate and understand differences in their own sense of self across different relationships and contexts (National Academies of Sciences, Engineering, and Medicine, 2019a). Settings and relationships that provide them with a sense of physical and psychological safety and belonging, opportunities for autonomy, intellectual challenge, and clear and culturally responsive norms and expectations can support adolescents’ capacities for self-regulation, independence, and decision making (Eccles and Roeser, 2011; Geisz and Nakashian, 2016; Gestsdottir and Lerner, 2008; Scales et al., 2011; Siegel, 2013).

During middle and late adolescence, youth are also considering their place in the world and their aspirations for life after high school as it relates to postsecondary education, skill development, and work and career possibilities. Opportunities for adolescents to contribute to their communities and critically consider the social world can support their identity and sociopolitical development (Watts and Guessous, 2006; Watts et al., 2011) and provide culturally relevant and meaningful experiences (Harper et al., 2018c). During middle and late adolescence, youth still have heightened sensitivity to peer influence and social belonging, yet as adolescents age their peers may become less important to their own self-evaluations (National Academies of Sciences, Engineering, and Medicine, 2019a). Further, both parents and nonparental adults (e.g., teachers, coaches, mentors) continue to provide important support for healthy identity development and autonomy seeking (National Academies of Sciences, Engineering, and Medicine, 2019a).

As with the literature on early adolescence, research on the role of out-of-school programs in middle to late adolescence is helpful in thinking

about the ways in which summer programs can support youth during this developmental period. As noted earlier, participation in out-of-school programs during adolescence may reduce risk-taking and anti-social behavior in both adolescence and young adulthood, especially for those youth experiencing the most risk factors (Mahoney, 2000). Additional research corroborates these findings and suggests that activity participation during middle and late adolescence may have both preventative and promotive effects. For example, one longitudinal study of adolescents in grades 7–12 drawn from the Childhood and Beyond⁴ study sample (Fredericks and Eccles, 2006) found that the duration (i.e., number of years) of involvement in extracurricular activities was associated with several positive developmental outcomes, including improvements in grades and psychological resilience. Further, for older adolescents, participation in extracurricular activities was associated with academic adjustment and psychosocial competencies. It should be noted that the sample in this study was majority-White, came from four school districts in Michigan, and was specifically chosen from districts where family and neighborhood factors were unlikely to pose a barrier to afterschool activity participation, making it difficult to generalize the findings to youth growing up in neighborhoods characterized by higher levels of poverty and other environmental barriers.

Another longitudinal study of mostly White youth (n = 1,259) from 10 school districts in working- and middle-class communities in Michigan (Eccles et al., 2003) found that activity participation in 10th grade had both promotive and preventative effects on several academic, occupational, and behavioral outcomes. Participation in a variety of types of activities, such as performing arts, pro-social activities, academic activities, clubs, or sports, had a positive impact across high school and into young adulthood. Yet participation in sports also had a potential negative affect, with athletes reporting higher levels of drinking in 12th grade in addition to positive educational and employment outcomes during high school and early adulthood.

As with childhood, during adolescence summer programming can offer important opportunities for youth to assert autonomy in their choice of activities, which itself is an important developmental task during this period. Further, summer can provide critical unstructured time that may counterbalance the stress of the academic year for students. Importantly, however, unstructured here does not mean wholly unsupervised, as unsuper-

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⁴ The Childhood and Beyond (CAB) project is a study of students’ achievement and learning experiences from K–12. The project began in 1987 and has conducted surveys and interviews with children and parents for more than 30 years. They cover a broad range of activities, behaviors and beliefs. For more information on the Childhood and Beyond (CAB) project, see http://garp.education.uci.edu/cab.html.

vised time is linked to increased engagement in risk-taking and anti-social behaviors, as noted throughout this chapter.

HOW DOES SUMMER AFFECT DEVELOPMENTAL TRAJECTORIES?

The committee found little systematic research concerning the impact of summer on the developmental trajectories of school-age children and youth across all four areas of well-being. In most cases, what we were able to find were sources of data pointing to seasonal differences in the rates of incidence. We identified far more information on how summer influences academic learning and obesity relative to other developmental outcomes of interest. It is also important to note that a number of the gaps in developmental outcomes between children and youth from higher and lower socioeconomic backgrounds and from different racial and ethnic groups are present before school entry, including gaps in the academic, social and emotional, and health domains. Thus, it must be acknowledged that it may be challenging for a single, standalone summer program to redress such gaps.

In the following, for each of the four domains we provide data and research on what is known about how summer influences these areas. Where no summer-specific information exists, we also look to what is known about out-of-school time generally (which includes summer and after school) that may be applicable to summer as well.

Safety and Pro- and Anti-Social Behaviors

As highlighted by the sections above, safety is foundational to physical and psychological health, well-being, and healthy development. We know that appropriate supervision is a key condition to ensure the safety of children and youth (Persson et al., 2007). Indeed, being unsupervised during out-of-school hours is associated with significant risks (Resiner et al., 2007). Summer is a potentially risky time for youth in that the amount of unsupervised time may be greater during the summer months than during the school year. While safety does not have developmental trends, per se, the characteristics of safe environments that are needed to support healthy development change as children’s motor, cognitive, and social skills develop. As such, some risks to safety are inextricably linked to other characteristics associated with children’s physical, psychological, cognitive, and social development.

We next discuss three key areas where we identified evidence of seasonal differences in relation to this domain: crime, pro- and anti-social behaviors, and substance use. Whereas we separate these areas for this discussion, there is some overlap. Certain risks to safety (e.g., peer victimization, exposure to violent crime) can result from other youth’s anti-social behaviors.

Further, substance use, generally defined as a risk-taking behavior, is also an act of delinquency, because youth are under the legal age for use even for substances that are legal for adults.

Crime

Seasonal patterns of crime exist and persist, despite overall reductions in crime over time. A study tracking violent and household property crimes from 1993 to 2010 found that victimization rates were higher during the summer than during any other season for most crimes, including household property crimes and violent crimes, with the exception of robbery and simple assault. However, among youth ages 12–17, simple assault victimization rates were lowest during the summer, starting when the school year ended, and were highest in the fall when the school year began, suggesting that violence may be occurring en route to or during school (Lauritsen and White, 2014).

Exposure to violent crime can damage children’s health and development (Osofsky, 1999), and it should be noted that juvenile crime also has implications for the youth who are the potential victims of it—when crime rates increase, so does the risk of victimization. Children and youth in low-income families and those in neighborhoods with concentrated disadvantage are affected by violent crime at higher rates than others. A recent report, using data from the National Crime Victimization Survey, found that people in households below the federal poverty level experienced more than double the rate of violent victimization as high-income households (Harrell et al., 2014). Neighborhoods with more concentrated disadvantage and greater segregation by race and ethnicity tend to experience higher levels of violent crime (U.S. Department of Housing and Urban Development, Office of Policy Research and Development, 2016).

Overall engagement in delinquency, defined by the U.S. Department of Justice’s Office of Juvenile Justice and Delinquency Prevention as “an act committed by a juvenile that would be criminal if committed by an adult” (Office of Juvenile Justice and Delinquency Prevention, 2019), typically increases from childhood to adolescence. Rates then decline with age, even for persistent offenders, with peaks in adolescence or during young to middle adulthood for different types of offenses (Sampson and Laub, 2003). National trends show that rates of juvenile crime and violence-related behaviors, such as carrying a weapon or being in or being injured in a fight, have declined overall since 1990 (Arnett, 2018).

Yet patterns of crime associated with in-school versus out-of-school hours also differ by type of crime. One study found that property crimes decreased by 14 percent on days when school was in session, suggesting a decrease in anti-social behavior when youth are supervised; it found further

that violent crimes increased by 28 percent on school days, suggesting that opportunities for youth to interact with each other are linked to juvenile violence (Jacob and Lefgren, 2003). Violent crime peaks in the immediate afterschool hours on school days and in evenings on nonschool days (Jacob and Lefgren, 2003).

Although most of what is known about the relationship of policing or police interactions to health and well-being has been based on adult experiences (although see Legewie and Fagan, 2018), the salience of adolescence as a critical developmental stage (Steinberg, 2014) suggests that experiences with the police may be particularly influential at younger ages and among school-age youth. Police interaction with youth have increased in recent decades due to their increase in schools (National Academies of Sciences, Engineering, and Medicine, 2019a). Negative interactions between police and youth “may produce cynicism and undermine legal socialization” (National Research Council, 2013, p. 194). Police are increasingly recognized as a significant social force shaping the development and well-being of youth, yet much remains to be learned about police-youth interactions at a population level. These unknowns include our currently limited understanding of how the unique context of summertime, and the associated time that students have off from school, may shape interactions between young people and the police (Geller, 2019).

Pro- and Anti-Social Behaviors

Both pro-social behaviors, those aimed at helping others (Eisenberg and Spinrad, 2014), and anti-social behaviors, such as aggression and delinquency, skipping school, and lying (Light et al., 2013) demonstrate some developmental and seasonal trends. Pro-social behaviors appear to increase from early childhood into elementary school (Eisenberg and Spinrad, 2014). However, varying trajectories of pro-social behavior from childhood into and through adolescence have been documented (Eisenberg and Spinrad, 2014). Some report a decline in the positive behaviors associated with social emotional and character development from middle childhood into adolescence, despite increased cognitive abilities that should, in theory, lead to increased moral reasoning and thereby pro-social behaviors (Luengo Kanacri et al., 2013; Washburn et al., 2011).

Others have documented increases or stability in pro-social behavior into and across adolescence (Eisenberg and Spinrad, 2014). Thus, different developmental patterns of pro-social trajectories have been found, yet overall, with some exceptions for particular types of behavior, prosocial behavior appears to decrease in early adolescence but then increase again in late adolescence (Eisenberg and Spinrad, 2014). Concurrently, increases in anti-social behaviors have been documented from ages 12–16

(Jessor and Jessor, 1977; Loeber and Burke, 2011; Nagin and Tremblay, 1999; Patterson and Yoerger, 2002; all as cited by Light et al., 2013). General patterns of anti-social behavior demonstrate that the vast majority of individuals desist from such behaviors in adulthood. Rates of anti-social behavior (i.e., arrests, delinquency) tend to increase across early to middle adolescence. These rates peak in late adolescence, and then decline; while for a smaller group of individuals—who have often tended to show earlier, more frequent, and more extreme anti-social behavior—anti-social behavior persists into and through adulthood (Moffitt, 1993).

In terms of seasonal patterns, in a longitudinal study of students (n = 5,742) from 11 rural and suburban middle schools across the western United States, Light and colleagues (2013) found decreases in anti-social behavior during each school year across grades 6–8, with increases between school years. The researchers could not conclusively say whether the increase in anti-social behavior that marked the beginning of the school year occurred over the summer or at the start of school year, or both. In a study of students (n = 5,581) from 37 middle schools across four communities, in which all the schools served a high proportion of students on free or reduced lunch, Farrell and colleagues (2011) found the opposite pattern for aggression. In this study, aggression demonstrated increases during the school year from sixth to seventh grade, but both physical and relational aggression decreased during the summers throughout the middle school years. They hypothesized that the pattern found by Light and colleagues (2013) was due to the start of the school year, because students attempt to re-establish peer social hierarchies after the summer. This research is consistent with crime statistics reported earlier, which find reduced rates of assault victimization for youth during the summer.

As noted earlier, participation in afterschool activities may be protective for youth at high risk of engagement in anti-social behaviors. Mahoney and Cairns (1997), in a longitudinal study of students (n = 392) from two middle schools that followed students into high school, documented that participation in an extracurricular activity was protective for students with the highest risk for school dropout. Mahoney (2000) then found that participation in extracurricular activity was associated with decreased school dropout and arrests among youth with multiple risk factors. Importantly, this depended on others in the youth’s peer group also participating in activities. In another study by Martin and colleagues (2007), Black males ages 13–17 who had previously been expelled or suspended from school showed improved school attendance and academic skills and a reduction in disciplinary actions after attending a 5-day-a-week afterschool program for 2 years. Of note, the program comprised a variety of components including tutoring, cultural and recreational activities, and nutritious meals. As discussed later in Chapter 5, youth involved in the juvenile justice system and

other youth considered at risk for anti-social behaviors can benefit from programming that supports their needs for skills that help them transition to adulthood (Ananthakrishnan, 2019).

Substance Use

National trend data reveal steady declines in adolescent substance use, including alcohol and cigarettes, between 1990 and 2017 (Arnett, 2018). Rates of drug use differ, with rates of marijuana use fluctuating over the years and rates of other drug use increasing in the 1990s and declining since then (Arnett, 2018). Use of e-cigarettes has increased in recent years for both middle school and high school age adolescents (Cullen et al., 2018).

Among youth, substance use, including use of alcohol, cigarettes, and drugs, generally increases from early to late adolescence (e.g., Farrell et al., 2005; Warren et al., 2016). Whereas we might expect substance use to increase during the summer, when adolescents may have more unsupervised time, the evidence is complicated. The National Survey on Drug Use and Health found that first-time use of alcohol, tobacco, marijuana, hallucinogens, and inhalants peaks in June and July (Substance Abuse and Mental Health Services Administration, 2012). However, a national survey examining overall past-month use of illicit substances found that past-month use of any illicit drug except marijuana is lower during the period when most students are on summer vacation and that fewer adolescents reported being approached by drug dealers in the summer than during other times of the year. However, alcohol use was higher in July (along with holidays and winter recess) than at other times of the year (Huang et al., 1999). Similarly, one study of middle school students at three urban public middle schools serving a predominantly Black student population from low-income families (Farrell et al., 2017) found that substance use decreases in the summers from grades 6–8.

Physical and Mental Health

Whereas there has not been much research focused on the relationship between children’s summertime experiences and their overall physical and mental health trajectories, there are several common health conditions in children where seasonality is known to play a role. There are also particular circumstances that children experience during summertime that may affect physical and mental health outcomes. In addition, the extent to which youth are managing an ongoing or emergent health issue can impact their engagement in summertime opportunities.

The three most common causes of mortality among children ages 5–14 are unintentional injuries, cancer, and suicide (Kochanek et al., 2019).

The three most common causes of mortality for adolescents and youth ages 15–19 are unintentional injuries, suicide, and homicide (Heron, 2019). A study of the 10 leading causes of death and injury in the United States from 1980 to 2016 found a distinct seasonal pattern of mortality from unintended injuries in males ages 5–14 that was similar across all regions (Parks et al., 2018). Seasonal variation also has been reported in common childhood conditions, including asthma, obesity, and mental and behavioral health conditions.

Injuries

Physical activity-related trauma, such as sprains, fractures, and contusions, sustained while engaging in sports or recreational activities is a primary cause of summertime pediatric injuries in western countries (Jespersen et al., 2014). A study in the United States of temporal variation in injuries associated with seven common recreational activities in children under age 18 examined emergency room visits logged into the National Electronic Injury Surveillance System (NEISS) between 2002 and 2006. It found that emergency room visits peaked in June for injuries from trampolines and scooters and in July for injuries from cycling and water activities. Injuries related to skating and playground activities peaked in April and September (Loder and Abrams, 2011).

A study of childhood trauma from injury found a similar pattern, with the highest number of childhood trauma victims seen in the emergency room in July, and twice as many children admitted from May to August as were admitted from November to February (Groh et al., 2018). A retrospective study of children (mean age of 5.9 years) with humeral fractures requiring surgery in Indiana also documented a significant increase in fractures in the summer, peaking in early July, with injuries occurring from playground equipment, furniture, climbing activities, sports, trampolines, bicycles, and all-terrain vehicles (Loder et al., 2012). Injuries from moped accidents in the United States were twice as common in youth under age 18 than adults in the summer, with the highest frequency in youth ages 14–18 (Johnson et al., 2016). Drowning is the leading cause of death by unintentional injury in children ages 1–4 and the second leading cause of death by unintentional injury in children ages 5–9 (Centers for Disease Control and Prevention, 2017). Whereas children who drown between ages 1–4 tend to drown in swimming pools, hot tubs, or spas, older children and adolescents who drown tend to do so in outdoor natural water settings. Males and Black children have higher rates of drowning. Swimming skills are associated with reduced rates of drowning. More Blacks report limited swimming skills than Whites, which may account for the disparity in rates of drowning (Gilchrist and Parker, 2014; Irwin et al., 2009). In a study of adolescents over age 16,

reasons for higher rates of drowning among males than females were swimming in high-risk situations, overestimation of swimming ability, and use of alcohol while swimming (Howland et al., 1996).

A study of heat-related injuries in Florida found that the rate of non-work-related emergency room visits was highest for adolescents ages 15–19 (60.41 per 100,000 person-years) and that the rate decreased as age increased, while the lowest rate of non-work-related heat-related injuries was among children under age 10 (9.83 per 100,000 person-years). However, the highest heat-related-injury death rates were for the elderly and those under age 5 (Harduar Morano et al., 2016).

Asthma

In the northern hemisphere, asthma episodes peak in the early fall, a trend hypothesized to be due to respiratory viruses (Johnston and Sears, 2006). However, this peak varies by geographic region in the United States, where it ranges from early fall to early spring (Wisniewski et al., 2016). In a 15-year study of prescription fill rates for asthma medication, the lowest fill rates were found to be in July, increasing in the autumn and through the winter, suggesting that prescription filling is reactive and follows disease exacerbation (Turi et al., 2018). However, deaths from asthma are more common in the summer months (Campbell et al., 1997; Weiss, 1990).

Obesity

Numerous studies have found an increase of childhood obesity in the summer. An analysis from the Early Childhood Longitudinal Study of body-mass index (BMI) measurements at the beginning and end of kindergarten and first grade showed that BMI increases more rapidly and more variably during the summer than during the school year. The same study found that the disparities in obesity prevalence between Black or Hispanic children and White children were largely due to increases in their BMI during the summer (von Hippel et al., 2007). In 2016, von Hippel and colleagues published an updated study, which found a similar gain in summertime BMI. However, this second study found no significant differences in summer weight gain by race or ethnicity. There were also no differences in summer weight gain between boys and girls, between children based on their families’ higher versus lower incomes, or between children based on maternal education or employment status (von Hippel and Workman, 2016). Similarly, in a five-year longitudinal study conducted in southeast Texas, children generally lost weight during the school year and gained weight during the summer without any racial or ethnic variation (Moreno et al., 2013).

However, other studies have found that summer affects childhood obesity differentially across groups of children and youth. Children who are in the highest BMI percentiles have been found to gain significantly more weight during the summer than children in lower BMI percentiles (Downey and Boughton, 2007), placing children with severe obesity at the greatest risk for summer weight gain. One study of third-, fourth-, fifth-, seventh-, and eighth-grade American Indian school children found that those who were at or above the 85th percentile for BMI experienced an increase in BMI during the summer, while for children below the 85th percentile there was no change (Smith et al., 2009). However, another study of American Indian children between kindergarten and first grade found no change in the velocity of BMI increase in the summer as compared to the school year (Zhang et al., 2011).

Various explanations have been advanced to account for increased weight gain among children and adolescents in summertime. Factors that have been proposed include decreased physical activity and increased sedentary behaviors, poorer nutrition, and lack of access to school interventions. We discuss these factors below, many of which disproportionately affect children and youth in disadvantaged neighborhoods. Many of these factors fit within the “structured day” hypothesis (Brazendale et al., 2017). During the school year, children and adolescents generally experience a more highly structured, consistent, compulsory, and supervised day than in the summer. During the summer, there may be greater nutritional, activity, and sedentary activity choices and more discretionary time to engage in media use and alter sleep times (Avery et al., 2017). In one study, adolescents who regularly participated in organized activities were at less risk for obesity than those who did not (Mahoney, 2011).

Physical activity and sedentary behavior. A review of the research on seasonal variation and physical activity among children and youth by Carson and Spence (2010) suggests that summer may be associated with increased physical activity for some children and youth in certain contexts, but the evidence is mixed. Furthermore, the relationship between seasonality and physical activity may vary based on geography, urbanicity, and climate. For example, in different parts of the world, rural youth may be more active in the warmer months and urban youth were more active in the colder months (Carson and Spence, 2010).

Lower physical activity and increased sedentary time in the winter have been found across all ages, ethnicities, and climates (Atkin et al., 2016; Kornides et al., 2018; Stalsberg and Pederson, 2010). Atkin and colleagues (2016) analyzed seasonal accelerometer data from 705 seven-year-olds in the Millenium Cohort Study in the United Kingdom and found that in all children moderately vigorous physical activity (MVPA) was lower in autumn and winter compared with spring. MVPA was lower in summer

compared with spring in boys, children of normal weight, those living in urban areas, those from high-income families, and on weekends. Sedentary time was greater in autumn and winter than in spring, and the seasonal effect was stronger during the weekend. Relative to spring, sedentary time in summer was lower on weekdays but higher during the weekend. Summer seems to be a time when activity and sedentary behavior are more variable between groups and during the week when compared to the school year (Atkin et al., 2015). No matter what the season, adolescents are not meeting daily physical activity requirements.

A prospective study of self-reported activity in adolescents (Kornides et al., 2018) found that 85 percent of adolescents did not meet the recommendation for MVPA (recommendation of 4 hours/week), and 91 percent did not meet the recommendation for vigorous physical activity (VPA; recommendation of 3 hours/week) for one or more seasons over the four study years. However, they were more likely to meet the MVPA requirements during the summer than in the winter. Even so, 60 percent of adolescents did not meet the moderate to vigorous physical activity requirements in the summer. Those least likely to meet these physical activity requirements were females, adolescents who had overweight or obesity, and older adolescents. When they compare the school year as a whole versus summer, many studies find a lower percentage of light-intensity physical activity and greater sedentary time, screen time, and sleep time during summer compared to the school year (Brazendale et al., 2018).

Zinkel and colleagues (2013) studied 162 school-age, sedentary Black and White youth based in or near the District of Columbia who were at risk for adult obesity to assess the potential impact of seasonal differences in total energy expenditure (TEE) on summer weight gain. When total and resting energy expenditure were measured throughout the year, no differences in energy expenditure were detected between summer and the school year, and the authors suggested that increased calorie intake through food and drinks may be the primary driver of summer weight gain (Zinkel et al., 2013).

Nutrition. Children and youth ages 6–19 engage in higher consumption of sugar-sweetened beverages and slightly lower intake of vegetables during school break (see Box 3-3), according to an analysis of the National Health and Nutrition Examination Survey (NHANES)⁵ for 2003–2008. Consumption of sugar-sweetened beverages and added sugar was higher for males, higher on weekends, and higher for older children (Wang et al., 2015b).

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⁵ The NHANES is a series of multicluster cross-section surveys conducted by the Centers for Disease Control and Prevention that are representative of the noninstitutionalized U.S. population. For more information, see https://www.cdc.gov/nchs/nhanes/index.htm?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fnchs%2Fnhanes.htm.

Another study found that consumption of sugar from more fruits, sweets, and desserts during summer resulted in an unhealthier high-sugar intake during the season (Brazendale et al., 2018).

Disruption of school interventions. School-based interventions for obesity have been successful during the school year (Wang et al., 2015a), but improvements in fitness, metabolic status, and percentage of body fat have been found to be reversed during the summer, with measurements returning to pre-intervention levels by the beginning of the next school year (Carrel et al., 2007). A small study of children in rural Wisconsin whose BMI was above the 95th percentile showed that positive results of a school-based obesity intervention (improvements in percent body fat, cardiovascular fitness, and fasting insulin) were lost during the summer break (Carrel et al., 2007). In two studies of school-based fitness interventions, improvements in fitness and body composition were lost during the summer (Gutin et al., 2008; Yin et al., 2012). In a 2-year community intervention involving more than 1,000 children in grades 1–3, BMIz⁶ decreased in children in the intervention community compared to children in the control groups. The next summer, when the intervention was less intense, there was no change in the BMIz scores between the intervention and control groups, possibly indicating a dose-response effect (Economos et al., 2013). Thus, it appears that interventions being continued into the summer may be important for maintaining obesity-related outcomes.

Neighborhood characteristics, physical activity, and weight gain. Although the associations between neighborhood characteristics and obesity in childhood are largely inconclusive, it is possible that neighborhood characteristics may influence children’s physical activity and eating during the summer in particular ways. High-poverty neighborhoods often lack basic infrastructure, with substandard housing stock, more abandoned and boarded-up buildings, inadequate municipal services, fewer retail facilities (e.g., supermarkets), more bars and taverns (Evans, 2004), and high levels of joblessness and crime, especially violent crime (Meade, 2014). Confronted with such conditions, many parents in distressed neighborhoods shield their children from the streets by limiting their outdoor time (e.g., DeLuca et al., 2011). One result is that between 0–6, children from higher-income families spend an average of 1,300 more hours in “novel contexts”—meaning contexts other than home, school, or in the care of another parent or a day care provider—than do children from lower-income families (Phillips, 2011, p. 207).

A study of the link between neighborhood environments and weight gain of almost 3,000 children in a midsized city in the South from predominantly Black elementary-schools and from lower-income families demonstrated that females and older children gained more weight in the summer compared to males and younger children. These patterns did not vary by

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⁶ BMIz = Body Mass Index z-score.

race with respect to summer weight gain. As in other studies, children who were overweight or had obesity gained more weight in the summer than children with normal weight. The study also showed that overweight children living near two or more small grocery stores gained less weight than overweight children who lived near just one or no stores; whereas whether or not the children lived within one mile of an active park was not associated with summer weight gain (Miles et al., 2018). Another study found that a lack of neighborhood safety is associated with a small reduction (8 minutes/week) in physical activity and a small BMI gain that did not change obesity status (An et al., 2017).

Mental Health

The only data regarding seasonal variations in mental health we identified involved mental health emergency visits. Emergency department (ED) data show fewer mental health–related emergency visits in the summer than in other seasons. Data from more than 20,000 children under age 17 in Alberta, Canada, from 2002 to 2008 document decreased presentations to EDs in urban and rural areas throughout Alberta for mental illness, substance use, or intentional self-harm in the summer. Visits for neurotic/stress-related disorders, mood disorders, intentional self-harm, substance abuse, and behavioral/emotional disorders decreased from May to July and then increased in August, September, and October (Ali et al., 2012). A retrospective study of psychiatric ED visits of children and youth ages 5–18 to a hospital in upstate South Carolina also demonstrated this seasonal pattern, with less frequent visits occurring in June, July, and August. The top reasons for admissions defined as mental health visits during the 5-year study period were aggressive behaviors (68%) and thoughts/actions of self-harm (27%); and the most common diagnoses were anxiety disorders (28%), disorders first usually diagnosed in infancy, childhood or adolescence (27%), mood disorders (19%), and substance-related disorders (10%) (Holder et al., 2017).

One review of the Nationwide Emergency Sample Department database (the largest all-payer ED database in the United States) examined suicide attempt–related ED visits from 2006 to 2013 for persons ages 10 and older, and found that such visits peaked for females ages 15–19 and males ages 20–24. Visits for attempted suicide were highest in the spring and fall. The largest number of visits occurred in May, and they were more common among persons in the lower-income quartiles (Canner et al., 2018). During an 8-year study of suicide ideation and suicide attempts in children, the lowest frequency occurred in the summer months, with the highest peaks in fall and spring (Plemmons et al., 2018).

Social and Emotional Skill Development

Social and emotional skill development, frequently referred to as social and emotional learning (SEL), has received increased attention over the past two decades in both school and out-of-school settings. Social and emotional skills include aspects of understanding and managing one’s own emotions as well as the social world, that is, both inter- and intra-personal competencies (Durlak et al., 2011; Elias et al., 1997; Greenberg and Weissberg, 2018; Weissberg et al., 2015). These skills help children and youth integrate their cognition, affect, and behavior (Weissberg et al., 2015). Although the category of SEL is frequently used broadly, individuals can have relative strengths and weaknesses among the various social and emotional skills. There are also important critiques of social and emotional learning from a lens of culture and equity (Jagers et al., 2018), discussed below, which underscore the importance of thinking about how these competencies are defined, what cultural biases those definitions may reflect, and the impact of that on populations of children and youth from different cultural backgrounds.

Developmental Trajectories of Social and Emotional Skill Development

Some researchers have examined seasonal patterns of anti-social behavior (discussed earlier; e.g., Light et al., 2013), but trends in the development of positive social and emotional competencies are not well understood. Differences between children in SEL-related competencies are already evident at kindergarten entry (Greenberg and Weissberg, 2018), which may give some indication, at least in early childhood, of the impact of out-of-school environments on social and emotional skills. Specifically, youth from families that are lower on the socioeconomic ladder and youth from disadvantaged racial and ethnic minority backgrounds tend to be assessed by teachers as having lower levels of social and emotional development in early childhood (Halle et al., 2009). In an analysis of the nationally representative Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K), Downey and colleagues (2019) documented income and Black-White gaps in teacher-assessed social and behavioral skills at kindergarten entry, and found that these gaps grew slightly between kindergarten and the end of second grade. They found no seasonal patterns, with gaps remaining consistent during the school year and over the summer.

Additional analyses of these data revealed gender gaps in social and behavioral skills (approaches to learning, self-control, and interpersonal skills) as assessed by teachers at kindergarten entry, with girls seen as entering school with more of these skills than boys. This gap between boys and girls continued to grow from kindergarten to the end of fifth grade

(DiPrete and Jennings, 2012). Whereas DiPrete and Jennings (2012) also found gaps in these skills by family income and by racial-ethnic background, the gender gap was larger than either of those gaps in kindergarten and continued to widen through fifth grade. The intersectionality of identities (e.g., gender and race) may be particularly important to consider in relation to teacher perceptions of social and emotional skills, as one study suggested that teachers monitor the behavior of Black boys more closely when they expect challenging behaviors (Gilliam et al., 2016).

One challenge with documenting the developmental trajectories of social and emotional skills is the limitation of current measurement approaches. The number of different definitions of social and emotional skills and learning, noted earlier, weak psychometric properties of the measures used, and differences in methods of assessment (self-report, observation, behavioral ratings, direct assessment) all limit the ability of the field to draw strong conclusions about the developmental properties of these skills (Card, 2017; Jones et al., 2016; McKown, 2017a, 2017b). It has been recommended that a strengths-based and low-stakes approach be taken to the measurement of social and emotional learning and skills. That is, rather than tying SEL assessments to accountability or decision making, it has been recommended to use them as feedback and to identify optimal ways of adjusting instruction to meet the needs of students. Along with this, it has been recommended to place a focus on formative assessment and implementation improvement (Taylor et al., 2018).

It is important to recognize that current conceptual definitions of social and emotional skills reflect the cultural norms and biases of the dominant cultural group engaged in the research and education fields: Whites of middle- to upper-class backgrounds (Deutsch, 2017; Jagers et al., 2018). This bias can also impact how adults perceive social and emotional skills in youth, which can in turn affect measurement of SEL. For example, well-documented discipline disparities in schools (see Gregory et al., 2017; Okonofua et al., 2016) suggest that teachers view the same behavior differently depending on who is displaying it, with harsher assessments of behavior for Black than for White youth (Carter et al., 2017; Gilliam et al., 2016; Okonofua and Eberhardt, 2015). This bias may then be reflected in teachers’ ratings of social and emotional skills in students, which are often used in studies of social and emotional skills in order to avoid self-report bias. At the same time, there is potential for SEL to redress rather than reify existing inequities if cultural issues are taken seriously. Jagers and colleagues (2018) coined the term “transformative SEL” to center issues such as power, privilege, social justice, discrimination, and self-determination within the field. They provide a thoughtful overview of the opportunities for equity to be addressed within core social and emotional competencies.

Academic Learning and Enrichment

Optimal academic development for children and youth throughout the school years—from kindergarten through grade 12—would have students move along paths that maximize their scholastic achievement while moderating disparities along lines of race, ethnicity, and family background. More specifically, the goal is that all children achieve at or above grade-level standards in the primary academic subjects at each grade level and be college and/or career ready at the end of high school.

Unfortunately, as a nation we fall short of the goal of high achievement equitably distributed across social lines. The achievement gaps that separate students from higher- and lower-income families and those that separate disadvantaged minority students from white students are large and longstanding. At school entry, disparities in a wide range of outcomes and competencies, including both knowledge and skills in areas such as early literacy and self-regulation, already exist between children from different economic and social backgrounds. Thus, it is critical to consider the role of early education in promoting equitable outcomes for children (Institute of Medicine, 2000).

Such gaps are not immutable, though, and real progress has been made in some areas. Trend data from the National Assessment of Educational Progress (NAEP) document large declines in the Black-White and Hispanic-White achievement gaps in reading and math over the past 40 years.⁷ As of 2012, both gaps had narrowed by 30 to 40 percent relative to the levels extant in the early 1970s, with the largest reductions registered during the decade of the 1970s and into the 1980s. Still, large gaps remain, ranging from 0.5 to 0.9 standard deviations across groups, ages, and domains of performance (Stanford Center for Educational Policy Analysis, nd).

The picture for family background is different. During the same time-frame that saw racial and ethnic achievement gaps decline appreciably, gaps across family income levels grew wider. In fact, the gap across family income levels now exceeds those across race and ethnicity. Among children born in the 1950s, 1960s, and early 1970s, those at the 10th percentile of family income averaged 0.9 standard deviations below those at the 90th percentile in reading. Today, for children born in the 2000s, the gap stands at 1.25 standard deviations (Reardon, 2013).⁸

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⁷ The NAEP testing program often is referred to as the Nation’s Report Card. Children are tested at ages 9, 13, and 17, most frequently in math, science, reading, and writing. The NAEP testing program began in 1969–1970. In recent years, testing has been done annually, although not all domains are tested each year. Sample sizes for assessments intended to generalize to the nation as a whole range between 10,000 and 20,000.

⁸ By way of comparison, in Reardon’s (2013) analysis of the Black-White gap for this same age cohort is a bit below 0.75 standard deviations, down from 1.2 standard deviations among children born in the 1950s.

These achievement gaps translate into later attainment gaps in high school graduation rates, college graduation rates, and employment rates (Cahalan et al., 2018; Economic Policy Institute, 2018; Vilorio, 2016). The importance of summertime for the learning opportunities available to young people in K–12 outside school will be observed most immediately in markers of academic achievement, but because successes and challenges in school anticipate successes and challenges in college and the workplace any such importance near term is certain to reverberate longer term. The remainder of this section examines possible links between summertime experience and academic development.

Evidence

The question of how summer influences the academic achievement and learning trajectories of children and youth has been studied more than questions regarding other domains. However, these studies do not always agree on precisely how summer influences academic trajectories. Studying the effect of summer is challenging, because schools do not typically test students in the fall and the spring. The seminal research is drawn from smaller, localized studies conducted in the 1970s and 1980s (Alexander et al., 2007; Entwisle and Alexander, 1990, 1992; Heyns, 1978), while more recent literature takes advantage of data from seasonal testing conducted by the national Early Childhood Longitudinal Study Kindergarten Class (K–2), from districts and states using the Northwestern Evaluation Association Measurement MAP Assessments (grades 3–8), and from summer intervention studies that examine summer learning in an experimental/control-group context.

Early Studies

Summer learning loss—the phenomenon of students forgetting some of what they learned during the school year—was first addressed in 1906, when William White, a teacher of mathematics in New Palz, New York, tested a handful of his fourth- and seventh-grade students on math facts before and after the summer vacation. Finding that students lost ground over the summer, White observed that “neglect for three months may blur the memory.”⁹

Recent studies, more rigorous than White’s, have asked a related question: Is summer learning loss more prevalent among children from lower-income families and among disadvantaged racial and ethnic minority groups than among children of more advantaged backgrounds? This line of research was

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⁹ Quoted in Pitcock (2018, p. 5).

launched by Barbara Heyns in her landmark study, Summer Learning and the Effects of Schooling (1978). Heyns examined the academic progress of sixth and seventh graders in Atlanta, Georgia, over an 18-month period, comparing school-year test score gains against gains over the months bracketed by successive school years (e.g., the summer between sixth and seventh grades). Children from lower-income families and Black children registered achievement gains close to those of their more advantaged counterparts during the school year, but over the summer months they lagged behind.

The next study of consequence was the Baltimore-based Beginning School Study (BSS), launched in the fall of 1982. In this research, the reading comprehension achievement gap separating children in lower-income families from children of middle-class family background increased from 0.5 grade equivalents in the fall of first grade to 3.0 grade equivalents in the spring of fifth grade; similar differentials were found on the math concepts and applications subtest of the California Achievement Test battery (Entwisle et al., 1997). Regarding the summer period, the achievement gap increase over this period traced back almost entirely to differences in summer learning, largely to the summers between first and second grade and between second and third grade. Then later, in ninth grade, the first year of high school, two-thirds of the extant reading comprehension gap comparing children from lower-income families against those from middle-income families (up to 3.5 grade equivalents at that point) was found to originate in differential summer learning over the elementary school years (Alexander et al., 2007).

In 1996, Cooper and colleagues (1996) reviewed the literature on summer learning loss, consisting of 39 studies, 13 of which lent themselves to rigorous quantitative meta-analysis. Learning patterns did vary by season, but they were not uniform across testing domains or student populations. Reading comprehension scores declined overall during the summer, more so among children from lower-SES backgrounds, while word recognition scores rose among children from middle class backgrounds and declined among children from lower-SES backgrounds. A composite of the reading domains favored upper-SES children over lower-SES children by 3 months over the summer months, while the Black-White difference was not significant.

Regarding math achievement, computation, concepts, and applications were examined separately, and a composite measure of all three was also examined. All children lost ground in math over the summer months (on the order of 2 months on average), the largest domain-specific loss being for computation.

Recent Studies

Both Heyns’ study in Atlanta and the BSS research in Baltimore, as well as many of the studies included in Cooper’s literature review, were local

studies each limited to a single city. A national perspective is afforded by more recent studies, including the massive database compiled by the Northwest Education Association (NWEA). In the studies cited below, NWEA’s Measures of Academic Progress (MAP) testing program assessed reading and math for nearly 20 percent of the school-age population in grades 2–9 in all 50 states from 2007–2008 through 2011–2012. Although MAP coverage is not strictly representative, the scope of this project affords a broad-based descriptive account of school-year and summer-achievement patterns.

MAP data show that learning slows during the summer months relative to the school year at all grade levels in both reading and math, with absolute declines during most summers. And these losses are appreciable, averaging, across grade levels and years, losses of 3 to 4 points against average school year gains of 4 to 16 points. As an example, over the summer following third grade, students lose nearly 20 percent of their school-year gains in reading and 27 percent of their gains in math. For the summer after seventh grade, the respective figures are 36 percent and 50 percent (Kuhfield, 2018b). On the other hand, MAP data also establish that not all students lose ground during the summer. Those who gain the most during the school year tend to lose the most over the summer months (Kuhfield, 2019), while differences by race/ethnicity in patterns of summer gains and losses are small (Kuhfeld, 2018a).

ECLS-K 1998–1999 and ECLS-K 2010–2011 also afford national perspective, albeit only for the early grades. Like the NWEA data, these are true panel studies in that they monitor the same children’s academic progress over time. One of the first studies to examine summer learning with these data (Downey et al., 2004) found large disparities across lines of family socioeconomic status (but not race/ethnicity) in reading and math gains over the summer between kindergarten and first grade (the only summer period monitored); however, this pattern was not replicated in subsequent analyses of these data using different psychometric methods (von Hippel and Hammock, 2019; von Hippel et al., 2018), while analyses of the more recent ECLS-K 2010–2011 cohort have yielded mixed results (Quinn et al., 2016; von Hippel et al., 2018).

Key Themes Across the Literature

The sections that follow summarize these and other key findings from the research, highlighting areas where we have greater or less certainty.

Academic Progress Slows During Summer Months. Research consistently demonstrates that academic progress slows during the summer months relative to the school year (Entwisle and Alexander, 1992, 1994; Heyns, 1978; Quinn et al., 2016; von Hippel and Hamrock, 2019). The slower rate

of academic learning during the summer makes sense, since children and youth are not receiving formal academic instruction during this time.

The Direction of Average Academic Progress Is Unclear. The seminal literature examining how summer affects academic achievement found that not only did academic progress slow during the summer months, it also faded. As noted, Cooper and colleagues (1996) found that on average children lose ground academically over the summer months in math and reading comprehension. However, more recent research shows a far less clear picture regarding whether children and youth, on average, are declining, maintaining, or slightly improving academic skills over the summer months. In most studies that find such declines (Atteberry and McEachin, 2019; Borman and Dowling, 2006; White et al., 2013; Workman and Merry, 2019), the magnitude is less than what was found in earlier literature. For instance, Workman and Merry (2019) find that average skills decline approximately 4 to 6 percent from the prior school year. Other studies find no loss or gain during the summer (Benson and Borman, 2010; McCoach et al., 2006; Ready, 2010; Zvoch and Stevens, 2013), small academic gains during the summer (Burkam et al., 2004; Fitzpatrick et al., 2011), and mixed results for different subjects, with a gain in one subject and no change in another subject (Downey et al., 2004; Hayes and Gershenson, 2016).

The Influence of Summer on Academic Trajectories Is Worse for Children and Youth from Lower-Income Families, Communities, and Schools. With few exceptions, research consistently finds evidence of differential outcomes for students based on family income. The seminal work on academic trajectories found higher rates of summer learning loss among children from lower-income families, particularly in reading (Cooper et al., 1996). Recent studies find that children from lower-income families learn less during the summer relative to their wealthier peers even if they do not experience absolute knowledge losses over the summer (Downey et al., 2004; McCoach et al., 2006; Benson and Borman, 2010; Ready, 2010; von Hippel et al., 2016; Benson and Borman, 2010; Kim, 2004; White et al., 2013). However, two studies in the early grades do not find differential loss (McCoach et al., 2006; von Hippel et al., 2018) and Gershenson (2014) finds mixed evidence that depends on the subject and model specification.

Studies also have found that children and youth living in neighborhoods with high poverty levels (Benson and Borman, 2010) or attending schools with high concentrations of poverty (White et al., 2013; Atteberry and McEachin, 2016) experience larger losses over the summer relative to peers in wealthier neighborhoods or schools.

Children from low-income families start kindergarten at a disadvantage, and that disadvantage persists through secondary school. The extent to which summer contributes to the achievement gap is unclear, with earlier research suggesting that it does and more recent studies more mixed in their conclusions. Nonetheless, as structured, the summer months are not helping to close the gap.

Racial Differences in Summer Academic Trajectories Appear to Be Driven by Family Income. In the United States, Black and Latinx children and youth are more likely to be from lower-income families than are their White peers. As a result, when researchers examine whether Black and Latinx children have differential rates of learning in the summer compared to their White peers, they can approach the question in two different ways. Studies that examine whether Black and Latinx children unconditionally have differential learning rates (not controlling for socioeconomic status (SES) differences among families) find that they fall behind their White peers over the summer months (Atteberry and McEachin, 2019; Kim, 2004; Quinn et al., 2016). However, studies that isolate race from family income find that Black and Latinx children have summer learning rates equal to those of their White peers (Benson and Borman, 2010; Burkam et al., 2004; Downey et al., 2004; McCoach et al., 2006).

This is a complicated, highly technical literature and therefore difficult to summarize. Quin and Polikoff’s (2017) stock taking and the conclusions that follow from it seem apt: “. . . summer loss and summer gap-growth occur, although not universally across geography, grade level, or subject.” More specifically:

• Test score disparities across social lines registered during the years prior to kindergarten exceed those that emerge over the early elementary years (summers and school years combined).
• Lower-income and minority youth do not always keep pace with their more advantaged counterparts during the school year.
• Summer learning differences by socioeconomic background and race/ethnicity are not always evident, consistently patterned, or as large as previously thought.

Poor children and disadvantaged minority youth enter school already behind, over time those achievement gaps persist, and in some studies they widen. Though we cannot parse with certainty what portion of these gaps and gap increases across social lines trace to the preschool years, to time in school, and to the summer months, it is certain that the summer period affords opportunities to mitigate them. It is also certain that these opportunities are not being fully exploited.

CONCLUSIONS

REFERENCES

Atkin, A. J., Sharp, S. J., Harrison, F., Brage, S., Van Sluijs, E. M. (2016). Seasonal variation in children’s physical activity and sedentary time. Medicine and Science in Sports and Exercise 48(3)(March), 449–456.

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