Effects of Applying Problem Based Learning (PBL) Strategy Use on Students’ Oral Vocabulary as One Aspect of Speaking Performance

This study’s main goal was to investigate how PBL, a learning strategy, might improve students’ oral vocabulary, which is one component of their speaking abilities in an EFL class with grade 11 students as the emphasis. The experimental (treatment) and comparative groups were the two research groups. Biftu Nekemte Secondary School was the site of the study (BNSS). The study’s population comprised all eleventh grade students enrolled in the academic year of 2014–2022. As a type of quasi-experimental research, the current study used a non-randomized pre-test, post-test comparison group design. The researcher used a multi-phase sampling strategy. 48 students from the experimental group and 49 from the comparison group took part in the study. The pre- and posttest instruments were adapted from the speaking performance rubric by Brown (2004). In fact, the researcher simply applied the rubric’s vocabulary part. The study’s quantitative portion was calculated using a number of statistical procedures. Calculations were made using descriptive statistics tools for the pretest and posttest groups to determine if the data was parametric or not. Additionally, separate t-tests were conducted. Cohen’s D (Effect Size) and Cohen’s Kappa (for inter-rater reliability) were also conducted, and they were equally significant. The usage of problem-based learning as a learning approach was found to considerably enhance EFL learners’ oral vocabulary skills, which is one facet of speaking abilities. Therefore, it is advised that various stakeholders take into account using PBL as a learning technique in EFL classes, especially for the teaching and acquisition of oral vocabulary.