The low average scores of students in the survey indicate the skill of students who are less in the problem-solving process. The student's skill in problem-solving in the learning process be measurable self-assessment and peer assessment.The objective of this research is to describe physics problem-solving skill after controlling student's prior knowledge. This research is a part of the dissertation research that was conducted at SMAN 7 Banjarmasin in 2015.The data were collected using prior knowledge instrument in early of the experiment and using the problem-solving instrument at the end of the experiment. This Study used a quasi-experiment with 2 × 2 factorial design (Wati 2016). The data was analyzed using descriptives statistics before calculated using analysis of covariance (ANCOVA).From data analysis, it can be shown that corrected means of (1) students prior knowledge all of thes experimental group was in poor category, (2) physics problem-solving skill of students who followed the the collaborative instructional model and were given peer assessment has the highest level than expository instruction model.