ABSTRACT
Accommodating student heterogeneity has consistently been a major instructional problem in schools. Regardless of how students are assigned to classes, with a typical elementary or middle-school class of 25 or more students, the teacher must address student heterogeneity in terms of students' prior knowledge, prerequisite skills, motivation, aptitudes, and attitudes toward learning. These cognitive, motivational, and attitudinal differences greatly affect what students learn, how quickly they learn, and how well they learn. As a result, teachers often become concerned about their instructional pace. They fear it may be too slow for the above-average students, causing them to become bored, and too fast for the below-average students, causing them to get lost, overwhelmed, or frustrated. Similarly, teachers are concerned about the difficulty of the tasks they assign during instruction, fearing that the tasks may be too easy and lack challenge for above-average students, while at the same time that they may be too difficult or complex for below-average students to experience success.
