Promoting the middle school students' engineering skills and conceptual understanding through STEM-based learning

Incorporating engineering in STEM education equips the students with the 21^st-century skills to design solutions for real-world problems, thus, STEM-based learning has been widely studied. This study aims to examine whether STEM-based learning can promote students' engineering skills and conceptual understanding. The participants were 68 seventh-grade middle school students, divided into 35 STEM and 33 non-STEM students. This study was conducted in environmental pollution topic where students design and make prototype to clean polluted air and water. The students' engineering skills during the project were measured by rubric while their conceptual understanding was examined by multiple-choice question. The independent t-test was employed for data analysis. The result showed that engineering skills of STEM and non-STEM students significantly improved (p <.001) from pre to post-test and had a large effect size (d_stem=5.87, d_non-stem=3.19). The N-gain value of STEM students (M=0.62, SD=0.14) was higher than non-STEM students (M=0.20, SD=0.06). However, although concept test scores of STEM students increased significantly (p<.001), STEM students' N-gain value (M=0.19, SD=0.30) was lower than non-STEM students (M=0.23, SD=0.20), indicating that the improvement is solely a learning effect, not because of STEM-based learning. To conclude, STEM-based learning successfully promotes the student's engineering skills, but not conceptual understanding.