Effectiveness of Early Literacy Instruction: Summary of 20 Years of Research

Children entering kindergarten vary greatly in their language and literacy skills. Therefore, up-to-date information about evidence-based practices is essential for early childhood educators and policymakers as they support preschool children's language and literacy development. This study used a process modeled after the What Works Clearinghouse (WWC) methodology to systematically identify effective early childhood curricula, lesson packages, instructional practices, and technology programs in studies conducted from 1997 to 2017. More than 74,000 studies were analyzed to identify interventions that improved students' performance in six language and literacy domains (language, phonological awareness, print knowledge, decoding, early writing, and general literacy). The study team identified 132 interventions evaluated by 109 studies that the study team determined were high-quality experimental or quasi-experimental studies. The WWC's evidence standards are used to assess the quality of an evaluation study and the strength of its claims about whether an intervention caused the observed effect on student achievement. To better understand the effectiveness of the interventions, their implementation characteristics and instructional features were coded for the relevant language and literacy domains. The findings revealed that instruction that teaches a specific domain is likely to increase performance in that domain. Interventions that teach language exclusively might be more beneficial when conducted in small groups or one-on-one than in larger group sizes. In addition, teaching both phonological awareness and print knowledge might benefit performance in print knowledge. Finally, some evidence indicates that instruction that teaches both phonological awareness and print knowledge might also lead to improvements in decoding and early writing performance.