This study aims to determine the effect of teaching the "Cell and Divisions" unit in the science course with concept maps on the academic achievement of 7th grade middle school students. In order to achieve the stated purpose, a mixed method approach using an explanatory sequential design was used. The study group of the research consisted of 30 middle school students studying in the 7th grade. Convenience sampling method was used in sample selection. In this five-week long implementation, the control group was taught by the teacher according to the current science curriculum in the textbook, while the experimental group was taught a lesson enriched with concept maps. Quantitative data were obtained with the Science Attitude Scale (SAS) and the Cell and Divisions Achievement Test (CCDAT). The "Semi-structured Interview Form" developed by the researchers was used as a qualitative data collection tool. Descriptive statistics, Mann Whitney U test and Wilcoxon Signed Rank test were used to analyze quantitative data. Qualitative data were analyzed descriptively by content analysis method. In the post-application analysis results, while there was no statistically significant difference between the pretest results of the control and experimental groups, statistically significant results were found in favor of the experimental group in the post-test academic achievement scores. Interviews with the students revealed that concept maps contributed significantly to their learning.