The research aimed to 1) to develop the lesson plans using the research-based learning integrated with cognitive training for grade 9 students and 2) to compare the students’ critical thinking skill between being taught by researched-based learning integrated with cognitive training and by traditional teaching method. The research samples using in this experimental research were grade 9 students of Phayamengrai School, Chiang Rai, Thailand in the academic year 2019 consisting of two samples: the experimental group taught by using research-based learning integrated with cognitive training was 30 students and the control group was 30 students taught by using the traditional lesson, selected by using cluster random sampling. The research instruments were the eight lesson plans focusing on earth and space science spending teaching 12 hours with the high reliability coefficient of 0.86 and the critical thinking skill test with the validity of 0.808. The data were analyzed by using mean, standard deviation and the MANOVA. The finding was the students’ critical thinking skills between two groups were significantly different. Obviously, the students in the experiment condition improved slightly more than those in traditional condition.