Exploring EFL Students' Perceptions of Using Online Tools for Vocabulary Learning: A Case Study at Tan Tien Secondary School in Dong Nai

Online Vocabulary Learning Tools (OVLTs) have spread rapidly among adolescent learners, yet the evidence base is concentrated on university populations and Western settings, leaving the self-directed practices of Vietnamese lower secondary students undocumented. This study describes the habits, attitudes and perceived effectiveness of OVLTs among Grade 7 and Grade 8 students at a provincial public school in Dong Nai, Vietnam. A quantitative-dominant mixed-methods design was used. A researcher-developed questionnaire — which separates dedicated vocabulary applications from general-purpose platforms repurposed for vocabulary learning, and separates perceived usefulness from perceived effectiveness at the measurement stage — was administered to four intact classes (172 distributed, 165 valid, 95.9%), and nine students were interviewed. Of the respondents, 145 (87.9%) reported prior OVLT use. General-purpose platforms dominated: online dictionaries (82.8%), YouTube (71.7%) and TikTok (64.8%) were used more widely than the leading dedicated application, Quizlet (58.6%), and significantly more often (M = 3.88 vs 3.27; Wilcoxon z = 5.47, p < .001, r = .53). Sessions were short: 71.7% of users typically studied for 15 minutes or less. Attitudes were positive on all three facets — perceived usefulness (M = 3.96), perceived ease of use (M = 3.92) and affective attitude (M = 3.86) — yet frequency was only moderate and correlated weakly with attitude (r = .21). Perceived effectiveness was ordered efficiency (M = 3.86) > retention (M = 3.79) > academic improvement (M = 3.65), and rose with usage frequency (r = .46, p < .001). Contextual conditions were consequential: digital distraction was the highest-rated contextual item (M = 3.88) and 20.6% of respondents lacked unrestricted device access. The findings position the teacher, rather than the tool, as the pivot between abundant informal exposure and deliberate vocabulary learning, and illustrate the limits of the Technology Acceptance Model when applied to early adolescents.