The objectives of this research comprised: 1)create a critical thinking exercise for Prathomsuksa 4 student which met the set criterion of standard. 2) to create scientific project design exercise for Prathomsuksa 4 student which met the set criterion of standard. 3) to compare the pre-test and post-test of critical thinking exercise. 4) to compare the pre-test and post-test of scientific project exercise and 5) to compare the quality of science project during pre and post using critical thinking skill and science project exercises. The sample used of this study was 28 students of Prathomsuksa 4 at Kokpanomdee School, Srimahososs District, Prachinburee Province, in the second semester of the academic year 2011 that selected by purposive sampling technique. The instruments used in this study were 1) the learning management plans of critical thinking exercises, 2) the learning management plans of science project exercises, 3) the learning achievement test about plants around us, 4) the learning achievement test about herb plants and 5) the evaluation form of science project quality.          The statistical techniques used Means, Standard Deviations, effective test (E1/E2) and t-test.
	The results of the study were as follow; 1) Critical thinking exercises had an efficiency of 85.42/89.16. 2) The results of effective test from scientific exercises had an efficiency of 86.74/88.69. 3) The progress result from critical thinking exercise showed that the result from post-test was significantly higher than the result of pre-test at .01 significant level. 4) The progress result from science exercise showed that the result from post-test was significantly higher than the result of pre-test at .01 significant level. 5) the quality of science project after using critical thinking skill and science project exercises was higher than before using at .01 significantly level.
