The present study compares traditional instructions and hands-on instructions on students' cognitive achievement for the topic 'Gas Pressure'. The participants in the study were students from a public middle school in Turkey. The research design was a quasi-experimental research design with a control group. In the control group, the teacher did the activities given in the course book whereas, in the experimental group, additional activities were performed by students. The results indicate that there was an increase in the correct response of students in both the groups after instructions, however, it was more in the experimental group. The wrong responses also showed a decrease in the experimental group as compared to the control group. Therefore, it can be concluded that hands-on instructions contribute more to students' cognitive achievement than traditional instructions.