The first school-level factor is a “guaranteed and viable curriculum.” I rank this as the first factor, having the most impact on student achievement. As indicated in Figure 2.3 (p. 19), a guaranteed and viable curriculum is primarily a combination of my factors “opportunity to learn” and “time” (Marzano, 2000a). Both have strong correlations with academic achievement, yet they are so interdependent that they constitute one factor.

Opportunity to Learn

Opportunity to learn (OTL) has the strongest relationship with student achievement of all school-level factors identified in Marzano (2000a). It was first introduced to the research literature more than 30 years ago by the International Association for the Evaluation of Educational Achievement (Wilkins, 1997) when it became a component of the First, and then later, the Second International Mathematics Study (FIMS and SIMS, respectively) (Burstein, 1992; Husen, 1967a, 1967b). Apparently, OTL began as an afterthought in FIMS when researchers became concerned that all students might not have had an equal opportunity to learn the items being used to assess their mathematics achievement (Wilkins, 1997). Consequently, various measures of OTL were devised and its relationship to mathematics achievement examined. The findings, which seem self-evident now, were somewhat of a surprise to the FIMS researchers as indicated by the following quote from a FIMS technical report (Husen, 1967b):

One of the factors which may influence scores on an achievement examination is whether or not students have had an opportunity to study a particular topic or learn how to solve a particular type of problem presented by the test. (pp. 162–163)