The aim of the study is to determine the effectiveness of The Common Knowledge Constructing Model (CKCM) on academic achievement and conceptual understandings of the 9th grade students on heat and temperature topic. Participants were 60 students (30 experimental and 30 control group) attending in the 9th grade of a high school in Gurpinar district of Van in the academic year of 2016-2017. Within quasi-experimental research design; The Heat and Temperature Conceptual Understanding Test (HTCUT), and the Heat and Temperature Achievement Test (HTAT) were used as data collection tools. While the qualitative data obtained with the HTCUT were analyzed with a graded scoring key, the quantitative data obtained with the HTCUT and the HTAT were analyzed with Wilcoxon Signed Rank Test and Mann Whitney U-Test. As the result of the study, it was found that the CKCM was effective in increasing academic achievement and conceptual understandings of the students. In addition, it was effective in replacing students' alternative concepts with scientific concepts on heat and temperature topic. To explore the influence of the CKCM on students' academic achievement and conceptual understanding more clearly, it is suggested to perform research on the use of the model in different subjects of physics course.