This study aimed to investigate the impact of using Science, Technology, Engineering and Mathematics Approach (STEM) on the development of creative thinking and science achievement of 360 grade students in basic education. The study sample consisted of (61) students from 3rd grade students of basic education in Muscat Governorate. They were divided into two groups: experimental group which consisted of (31) students who studied the science by (STEM) approach through the teacher guide for integrated activities which has been designed specifically for the purpose of this study, and control group which consisted of (30) students who studied by the conventional method. The study lasted for (15) weeks during the second semester of the academic year 2013/2014. To answer the research question, Torranc test for creative thinking was used with a reliability value of (0.84), and an achievement science test was constructed on involving (16) essay and multiple choice questions. That test was verified by arbitrators and the coefficient of reliability value was (0.75) which is acceptable. Results revealed that there were statistically significant differences between the two groups in creative thinking and science achievement in favor of the experimental group. The study also showed that there was a growth of three learning levels (knowledge, application, reasoning) in favor of the experimental group on posttest. Accordingly, the study recommended the importance of training students to use the STEM activities in science curriculums, because of their positive impact on the development of creative thinking and science achievement. Holding training workshops for teachers and supervisors on explaining how the integration of science, technology, engineering and mathematics, and employing appropriate attitudes and activities from the students real life.