An Investigation of the Impact of Science Lessons Based on UbD Practices on Middle School Students' Achievement and 21st Century Skills

The aim of this study is to examine the impact of implementing the “Human and Environment” unit in the 5th-grade Science curriculum revised in 2018 according to the Understanding by Design (UbD) approach on students’ academic achievement and 21st-century skill levels. A needs analysis was first conducted at a public middle school in Istanbul, Türkiye. Based on the findings of this analysis, a 20-hour UbD-based instructional plan was developed and implemented with the experimental group. The study was limited to the “Human and Environment” unit of the 5th-grade Science course during the second semester of the 2023–2024 academic year, and UbD practices were applied only within this unit. The duration of the research was five weeks, corresponding to the instructional period of the selected unit. The teaching process was implemented as planned throughout the experimental phase. A quantitative research method was adopted, utilizing a pretest–posttest control group experimental design. Achievement and skills tests were administered to both the experimental and control groups before and after the intervention. A total of 58 students participated in the study, with 29 students in each group. The quantitative data obtained were analyzed using dependent and independent samples t-tests, based on the assumption of normal distribution. The results revealed statistically significant differences in favor of the experimental group between pretest and posttest scores, as well as between the posttest scores of the experimental and control groups. These findings demonstrate that the UbD approach is effective in enhancing students’ academic achievement and skill levels.