Effectiveness of L2 Instruction: A Research Synthesis and Quantitative Meta‐analysis

TLDR

The generalizability of L2 instruction findings is limited by a lack of rigorous empirical operationalization and replication of core constructs. The study systematically synthesized and meta‑analyzed experimental and quasi‑experimental research on L2 instruction effectiveness from 1980 to 1998. The authors applied systematic procedures for research synthesis and meta‑analysis to aggregate data from 49 studies. The meta‑analysis revealed that focused L2 instruction produces large target‑oriented gains, explicit instruction is more effective than implicit, Focus on Form and Focus on Forms yield equivalent large effects, effectiveness is durable, outcome measures influence effect size, and enhanced research practices are recommended.

Abstract

This study employed (and reports in detail) systematic procedures for research synthesis and meta‐analysis to summarize findings from experimental and quasi‐experimental investigations into the effectiveness of L2 instruction published between 1980 and 1998. Comparisons of average effect sizes from 49 unique sample studies reporting sufficient data indicated that focused L2 instruction results in large target‐oriented gains, that explicit types of instruction are more effective than implicit types, and that Focus on Form and Focus on Forms interventions result in equivalent and large effects. Further findings suggest that the effectiveness of L2 instruction is durable and that the type of outcome measures used in individual studies likely affects the magnitude of observed instructional effectiveness. Generalizability of findings is limited because the L2 type‐of‐instruction domain has yet to engage in rigorous empirical operationalization and replication of its central research constructs. Changes in research practices are recommended to enhance the future accumulation of knowledge about the effectiveness of L2 instruction.