A search of published and unpublished articles focused on those that met the following criteria:
The studies involved elementary (K-6) children identified as English language learners or language-minority (e.g., Hispanic) students
Schools or classrooms using each program had to be compared to randomly assigned or well-matched control groups
Study duration had to be at least 12 weeks
The language of instruction was the same in experimental and control classes
Outcome measures had to be reliable and valid assessments of the reading skills being
taught in all classes
The review placed particular emphasis on studies in which schools, teachers, or students
were assigned at random to experimental or control groups
Program Ratings Basis
Programs were rated according to the overall strength of the evidence supporting their effects on reading achievement. Effect size (ES) is the proportion of a standard deviation by which a treatment group exceeds a control group. Large studies are those involving a total of at least 10 classes or 250 students. The categories are as follows:
Strong Evidence of Effectiveness: At least one large or two small randomized studies with median ES= +0.20 or more.
Moderate Evidence of Effectiveness: At least two large or four small studies (randomized and matched) with median ES= +0.20 or more.
Limited Evidence of Effectiveness: At least one qualifying study with median ES=+0.10 or more.
No Impact: Studies show no significant differences.
N No Qualifying Studies: No studies met inclusion standards.
The Best Evidence Encyclopedia is a free web site created by the Johns Hopkins University School of Education’s Center for Data-Driven Reform in Education (CDDRE) under funding from the Institute of Education Sciences, U.S. Department of Education.