In junior high school English education

vocabulary learning is foundational to language competence

and memorization speed is a key indicator of lexical processing efficiency. Eighth-grade underachievers often struggle with slow vocabulary learning due to phonetic difficulties

low motivation

and over-reliance on rote memorization. Based on Dual Coding Theory

this study developed a multimodal teaching model integrating short videos

vocabulary cards

and group interaction. A 6-week quasi-experiment with 60 eighth-grade underachievers compared multimodal intervention (experimental group) with traditional single-modal teaching (control group). SPSS analysis showed that multimodal teaching significantly improved students' vocabulary memorization speed

with acceptance of the method strongly correlated with learning gains. It also enhanced students' concentration

response speed

and classroom participation. The findings validate multimodal teaching's effectiveness for underachievers

provide an operable framework for frontline teachers

and enrich empirical research in this field.