knowledge as it is understood today; to be sure, subsequent work is already under way in each area that will refine, and may overturn, current understanding. It is always difficult to assess the progress of a line of research at a given point in time; as Imre Lakatos once wrote: “. . . rationality works much slower than most people tend to think, and even then, fallibly” (1970, p. 174).

A final point of clarification is warranted. In this chapter we rely on the metaphor of “accumulating” knowledge. This imagery conveys two important notions. First, it suggests that scientific understanding coalesces, as it progresses, to make sense of systems, experiences, and phenomena. The imagery also connotes the idea that scientific inquiry builds on the work that has preceded it. The use of the word “accumulation” is not, however, intended to suggest that research proceeds along a linear path to ultimately culminate in a complete and clear picture of the focus of inquiry (e.g., education). Again, as we show through several examples, science advances understanding of various phenomena through sustained inquiry and debate among investigators in a field.


In this section we provide examples of how scientific knowledge has accumulated in four areas. First, we describe the progression of scientific insight in differential gene activation, a line of inquiry in molecular biology that began 50 years ago and laid the foundation for today’s groundbreaking human genome project. Next, we trace advances in understanding how to measure and assess human performance, including educational achievement, that have evolved over more than a century. We then describe two controversial but productive lines of research in education: phonological awareness and early reading skill development, and whether and how schools and resources matter to children’s achievement.

These examples are provided to illustrate that lines of scientific inquiry in education research can generate cumulative knowledge with a degree of certainty and that they do so in ways similar to other scientific endeavors. To be sure, the nature of the work varies considerably across the examples. We address broad similarities and differences among disciplines and fields in Chapters 3 and 4. The lines of inquiry in this chapter demonstrate how knowledge is acquired through systematic scientific study.

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