This experimental research aimed to 1) compare academic achievement in grammatical knowledge between an experimental group taught with the mind map concept and a control group taught with inductive concept and 2) compare the experimental and control group participants'satisfaction with the management of instructional activities to develop grammatical knowledge after being taught through the mind map concept.A total of 40 Grade 8 Thai students attending an English class in the second semester of the 2020 academic year were recruited through a simple random sampling approach.The sample was divided into two groups, with 20 students in the experimental group and 20 in the control group. The research instruments consisted of 1) a mind map lesson plan; 2) an inductive lesson plan; 3) an academic achievement test; and 4) a satisfaction questionnaire. Descriptive statistics (mean scores and standard deviations) and inferential statistics (independent samples t-tests) were employed to analyze the quantitative data collected in this study. The findings demonstrate that the experimental group participants improved their academic achievement in grammatical knowledge more than the control group participants at the .01 significance level. In addition, the experimental group participants were significantly more satisfied with the management of the instructional activities to develop grammatical knowledge than the control group participants at the 0.01 significance level.