This research report aims to compare the effectiveness of traditional methods and collaborative teaching methods in improving the learning outcomes of grade 8 students in the subject of work-energy.The research was conducted at a high school in Phnom Penh, using a quantitative data collection method. A total of 92 students were selected using the Purposive Sampling Method and divided into two groups: Grade 8D1, a traditional teaching group of 44 students, and Grade 8C1, a cooperative teaching group of 48 students. The instruments used in data collection were pre-tests and post-tests focusing on the content of the physics lesson on potential energy and kinetic energy. The collected data were analyzed using Microsoft Excel (HAD 18) and T-test statistical analysis to compare the results. The results showed that the pre-test scores of both classes were similar (p-value = 0.110 > 0.05),
while the post-test showed that the cooperative teaching class had a better average score
(Mean=26.15) compared to the traditional teaching class (Mean=21.14) and (p-value =
0.001 < 0.05). Statistical analysis of the t-test confirmed that the cooperative teaching method was more effective than the traditional teaching method in increasing students' learning outcomes in the subject of Physics in Grade 8. However, since this research focused on the subject of Physics in Grade 8, future researchers should expand the scope of the research by testing the use of cooperative teaching and learning methods in Physics at other grade levels or other subjects to further understand the effectiveness of teaching and learning through the use of cooperative teaching and learning methods. Key words: Traditional methods, Cooperative Learning methods, and Learning outcomes