This research has been conducted to evaluate the effects of integrated science, technology, engineering and mathematics (STEM) education on academic achievement, reflective thinking skills towards problem solving and permanence in learning in science education. This study, which used pre-test-post-test and semi-experimental model with permanence test, control group as a research model, was conducted with 44 students attending to the 6th grade of a public school in 2015-2016 academic year. The study consisted of the control group with constructivist teaching and the experimental group with integrated STEM education. Academic achievement test and reflective thinking scale towards problem solving were applied. In SPSS 24 package program, analysis of quantitative data was performed using t-test and Mann-Whitney U test. In conclusion, the integrated STEM education does not significantly increase success, reflective thinking skills towards problem solving and their effects on permanence according to constructivist teaching, but provides positive contributions to academic achievement.