Evaluating Metaverse-based L2 Vocabulary Learning Effectiveness Using a Proposed Metric of Vocabulary Forgetting Percentage

Vocabulary gain and retention are key metrics in second language (L2) vocabulary learning, yet they often overlook the proportional loss of learned vocabulary over time. This study introduces a percentage-based metric—Vocabulary Forgetting Percentage (VFP)—to address this limitation. A quasi-experiment involving 50 Chinese middle school EFL learners compared metaverse-based vocabulary learning (MG) with slides-assisted learning (SG). Across three sessions, participants learned equivalent vocabulary content and completed pretests, immediate post-tests, and delayed post-tests. Independent-samples t-tests were used to compare vocabulary gains, retentions, and VFPs.