Writing skills development and vocabulary learning using Instagram in an EFL Omani context

Developing sufficient writing skills and an adequate vocabulary remains a persistent challenge for EFL learners, particularly in contexts where exposure to English beyond the classroom is limited. Traditional instructional approaches often fail to provide learners with meaningful, multimodal input that supports vocabulary retention and its practical use in written production. In response to these challenges, this study aimed to investigate the effectiveness of Instagram as a multimodal learning tool for enhancing vocabulary acquisition and writing skills among Omani EFL university students who took the General Foundation Program (GFP). To this end, the study adopted a quasi-experimental pretest–posttest design and involved 60 EFL learners (7 males and 53 females) from four intact classes at an Omani university. Participants were assigned to three experimental groups and one control group. The experimental groups received Instagram-based instruction through different modalities: words with images (G1), words with images and pronunciation (G2), and words with images presented in contextualized texts (G3). The control group received vocabulary instruction through conventional teaching methods. Data were collected through the administration of the Updated Vocabulary Levels Test (UVLT), general writing tests, and five researcher-developed vocabulary test sets targeting both receptive and productive knowledge. The vocabulary tests were organized into five instructional sets, each of which was administered following a repeated-measures design consisting of a pretest, an immediate posttest administered after the treatment, and one or more delayed posttests. This design allowed for the assessment of both immediate learning gains and retention over time for each vocabulary set. In addition, general writing and vocabulary size tests were administered as pretests and posttests at the beginning and end of the instructional period, with Posttest Set 3 Task 5 (free writing) administered in the middle of the intervention. The treatment was implemented over a three-week period, comprising 12 instructional sessions. The results indicated that while all groups demonstrated significant improvements in vocabulary knowledge and writing outcomes, the experimental groups significantly outperformed the control group in vocabulary comprehension, production, retention, and overall writing performance. Among the experimental groups, learners exposed to multimodal input combining words and images (G1) achieved the highest gains in vocabulary size, while learners exposed to multimodal input combining words, images, and audio (G2) achieved the highest gains in target, receptive, and productive vocabulary knowledge. The group receiving words, images, and contextualized texts (G3), however, demonstrated the most significant improvement in writing performance. Furthermore, a positive correlation was found between vocabulary gains and writing performance, reinforcing previous research that highlights the role of vocabulary mastery in the development of writing skills. The findings provide empirical support for integrating multimodal, social media–based instruction in EFL contexts to enhance vocabulary learning and written production.