AI-assisted instruction, the application of techniques and methods based on artificial intelligence in teaching, has attracted more attention recently. The aim of this study was to investigate whether using AI-based techniques for teaching vocabulary can positively affect and enhance learning among lower and upper intermediate language learners in language institutions. To this end, of 680 language learners enrolling in lower and upper intermediate level courses in a language school in Kermanshah, a total of 132 learners were randomly selected. After conducting a placement test, members of the sample group were allocated to four classes, of which two were lower intermediate and two upper-intermediate, all classes having the same number of learners with different degrees of proficiency in lower and upper intermediate levels. One lower intermediate class and one upper intermediate class received AI-assisted instruction in form of using Google Search Word Coach and querying Chat GPT for word grouping, synonyms and antonyms. Other factors and parameters were all identical in all the four classes to effectively control for the effect of unintended variables. After two months of receiving AI- assisted instruction twice a week, learners of the experimental group who received AI-assisted instruction in addition to non-AI instruction common between all the four classes, outperformed the control group in the vocabulary test given at the final stage of the study. The results of the test showed that AI-assisted teaching and AI-based techniques can positively affect and effectively enhance vocabulary learning in lower and upper intermediate levels.
