Educational tests are sometimes viewed as no more than measuring instruments, neutral indicators of learning outcomes. For more than a century, though, tests and assessments have been used in the United States to influence curriculum, allocate educational resources and opportunities, and influence classroom instructional practices (Haertel and Herman 2005). It is argued in this chapter that the idea of opportunity to learn (OTL) offers a useful lens through which to understand these many consequences of testing policies and practices, both positive and negative. Whenever assessment affects instructional content, resources, or processes, whether by design or otherwise, it is affecting OTL.

After framing the interplay of assessment with conceptions of OTL in terms of (1) content taught; (2) adequacy and allocation of educational resources; and (3) teaching practices, the chapter turns to five cases that illustrate some of these intersections. First considered is the intelligence-testing movement of the early twentieth century. This was a well-intentioned but unfortunate attempt to use testing to guide more efficient resource allocation. Second is Tyler's Eight-Year Study in the 1930s. This study reflected the designers' deep understanding that neither curriculum content nor instructional practices could be changed fundamentally unless consequential examinations were changed at the same time. The third case considered is the minimum competency testing (MCT) movement of the 1970s and 1980s, which prompted litigation leading to the legal requirement that students have a fair opportunity to learn what is covered on a high school graduation test.