Jean Stockard, Timothy W. Wood, Cristy Coughlin, Caitlin Rasplica Khoury:
The importance of explicit and systematic instruction has become a central element of discussions of effective instruction (e.g., National Reading Panel, 2000). Direct Instruction (DI), developed by Siegfried Engelmann and his collaborators beginning in the 1960s, is often cited as an example. Over the past half century the corpus of DI curricular materials has grown as has the literature evaluating its effectiveness. This article presents a quantitative analysis of this effectiveness literature. Although the term direct instruction (lower case and sometimes referred to as “little di”) has been used to refer to a broad set of educational programs that incorporate elements of systematic or explicit instruction, our focus is only on Direct Instruction (capitalized) in the Engelmann–Becker tradition (Engelmann & Colvin, 2006).