Individuals attempting to study remotely during the COVID-19 lockdown will find that blended learning is a helpful solution and results in a significant increase in learning engagement. The best benefits for teachers and students are obtained by maximizing the advantages of each teaching method and by combining the advantages of online and face-to-face instruction. The study aims to investigate the effectiveness of the flex model of blended learning in teaching the mathematics subtopic of coordinates in the plane through the improvement of students' academic achievement, self-study skills and learning attitudes. A quasi-experiment was conducted to compare the academic achievement, self-study skills and learning attitudes of 46 students in the control class who used traditional methods to those of 44 students in the experimental group who used the blended learning model. The pre-and post-test results, observations, and student opinion survey were used to compile data, which were then analyzed quantitatively (with SPSS) and qualitatively. The study confirmed that blended learning positively impacts students' academic achievement in the experimental class compared with the control class (Sig. (2-tailed) = 0.001 and SMD = 0.6717), as demonstrated by the outcomes of the independent t-test analysis of the two groups in the post-test phase. In addition, observations and student opinion survey results also indicated that blended learning increased student interactions with teachers and improved students' academic achievement, self-study abilities and learning attitudes. Due to time constraints, not all the students who participated in the experiment could make progress. On the other hand, the study's relatively small sample size gave the impression that the results were only partially representative of the population. As a result, additional studies focusing on improving the effectiveness of teaching and learning within different blended learning models, broadening the scope of research on the influence of blended learning in other subjects, or increasing the sample size can all be considered.