The Use of an Instrumental Language in Teaching Turkish as a Foreign/Second Language: An Experimental Study on Learner Perceptions and Academic Achievement

This convergent mixed-methods study investigates international learners’ perceptions and academic outcomes associated with the strategic use of English as an instrumental language in Turkish as a foreign/second language (TFL) instruction. Combining a survey of 113 multinational learners with a 6-week quasi-experimental intervention at the B2 level (experimental group, n = 10; control group, n = 12), the study contrasts self-reported skill priorities with objective post-test performance. Survey findings indicate that learners prioritized instrumental language support primarily for grammar (M = 3.01) and vocabulary (M = 2.97), while viewing it as least necessary for writing and speaking. Conversely, post-intervention achievement comparisons revealed a skill-specific paradox: while no statistically significant differences emerged in grammar, vocabulary, reading, listening, or writing, the experimental group achieved significantly higher speaking scores (p = 0.007, r = 0.67) than the target-language-only control group. Qualitative responses suggest that instrumental language availability may function less as a metalinguistic grammar tool and more as an affective scaffold and psychological safety net, consistent with the possibility that it mitigates anxiety and facilitates communicative engagement, although these affective mechanisms were not directly measured. These preliminary findings support a judicious, skill-differentiated pedagogical model wherein Turkish remains the primary instructional medium while strategic cross-lingual resources are preserved for cognitively complex and emotionally demanding speaking tasks.