Education is currently demanded to be able to provide 21st century skills to students so that they can be successful in the world of work and life in the future. One of the 21st century skills of particular concern is Collaborative Problem Solving (CPS) which plays an important role for students to be able to solve a problem collaboratively. This study aims to obtain an overview of CPS skills of students in the pursuit of physics. CPS is analyzed through two domains, social skills and cognitive skills. The subjects in this study were students of grade 10 in a public high school in Riau. Data is collected by giving problems of application of parabolic motion in everyday life. Students’ answers on answer sheets and recorded conversations of students are then analyzed using a rubric of CPS skills. The results showed that CPS skills of students in social skills and cognitive skills are still dominated in the low and middle categories. This result does not contain all the indicators developed by Hesse et al. several obstacles were also found in the assessment process. For this reason, further research is recommended to assess all indicators and use computer-based assessments.

This study aims to describe the use of project-based learning model to improve students' cognitive skills after participating in the project-based learning process. This study employed a quantitative approach using experimental method. The design used in this study was non-equivalent control group design. This study was conducted at SD A, SD B, and SD C Cirebon with 105 fourth graders as the research subjects. The subjects, consisting of 72 students in the experiment group and 33 students in the control group, were selected using simple random sampling technique. The instrument used was test in the form of pretest and posttest. Students' cognitive skills were measured based on the improvement in students' learning outcomes by comparing the result of pretest and posttest. From the result, it can be concluded that project-based learning can improve students' cognitive skills of four graders for animal life cycle lesson. The average learning outcomes increase from sufficient to good category. Classical learning mastery increases from less good to excellent category.