Education research. Instructional complexity and the science to constrain it.

935 EDUCATIONFORUM S cience and technology have had enormous impact on many areas of human endeavor but surprisingly little effect on education. Many large-scale fi eld trials of science-based innovations in education have yielded scant evidence of improvement in student learning (1, 2), although a few have reliable positive outcomes (3, 4). Education involves many important issues, such as cultural questions of values, but we focus on instructional decision-making in the context of determined instructional goals and suggest ways to manage instructional complexity. Ambiguities and Contexts in Instruction Many debates about instructional methods suffer from a tendency to apply compelling labels to vaguely described procedures, rather than operational defi nitions of instructional practices (5, 6). Even when practices are reasonably well defi ned, there is not a consistent evidential base for deciding which approach is optimal for learning. Empirical investigations of instructional methods, including controlled laboratory experiments in cogni-tive and educational psychology, often fail to yield consensus. For instance, controversy exists regarding benefits of immediate (7) versus delayed feedback (8), or use of concrete (9) versus abstract materials (10). Further complicating the picture is that results often vary across content or populations. For example, instruction that is effective for simple skills has been found to be ineffective for more complex skills (11), and techniques such as prompting students to provide explanations (12) may not be universally effective (13). Effectiveness of different approaches is often contingent on student population or level of prior achievement or aptitude. Some approaches, for example, may be particularly effective for low-achieving students (14, 15). Although specifi c instructional decisions may be useful at the level of the individual student (e.g., will this student learn better right now if I give her feedback or if I let her grapple with the material for a while?), the search for general methods that optimize the effectiveness, effi ciency, and level of student engagement is more challenging. Of the many factors that affect learning in real-world contexts, we describe three of particular importance: instructional technique, dosage, and timing. How choices on one dimension can be independently combined with choices on other dimensions to produce a vast space of reasonable instructional choice options is shown in the fi gure (Fig. 1). Instructional techniques. Many lists of learning principles suggest instructional techniques and point to supporting research (12, 16). Each list has between 3 and 25 principles. In-depth synthesis of nine such …