Youth Development Study, almost one-half of the employed seniors were saving at least part of their earnings for their future educational expenses [Call, 1996a].) If working is associated with higher grades under certain conditions that are under the students' control (such as the saving of earnings for college or the limiting of work's intensity), the effects of employment could well be due to selection. That is, the students' motivation to attend college or their concern about having sufficient time for their school work would likely encourage them to limit their hours of work and would explain any positive associations between paid work and achievement.
It may seem paradoxical that working does not have a more consistent effect on academic performance. Two recent studies report that neither employment status nor work intensity influences the amount of time spent doing homework (Mortimer et al., 1996; Schoenhals et al., 1997). Steinberg and Cauffman (1995) suggest that because the national average for time spent on homework is so low (fewer than 4 hours per week), employment is unlikely to diminish students' already very modest involvement in this activity. Teachers may also lighten homework assignments if they know about their students' work schedules. For the inconsistent findings with respect to work's effect on grades, there is some evidence that employed students may select undemanding courses so as to maintain high grade-point averages despite their jobs (Steinberg and Cauffman, 1995).
Very little attention has been given to the quality of students' jobs (in contrast to the intensity of their work) as a factor influencing their educational performance and attainment. However, Barling and colleagues (1995) report that the amount of time spent doing homework does not decline with hours of work when adolescents report using skills to a great extent in their jobs and having a very clear understanding of their roles as workers. When jobs entail little use of skills or clarity of roles, the amount of time spent studying declines with increases in the number of hours worked. (This cross-sectional study did not enable controls for prior experiences of the students that might have accounted for their having different job types.)
There is some emerging evidence from school-to-work programs that integration of school-based and work-based learning may help to overcome some of the negative effects on educational attainment