This study aims at examining the effects of use of simulation technique and worksheets together on the subject of matter and its cycles in science and technology lesson of primary education 8th grade students on hypothetical, correlation and combinational thinking which are among the formal operational stages. Simple experimental method was used in the present study. Study group of the research comprises of 15 8th grade students studying in a primary school in Akcaabat district of Trabzon province. The prepared Matter Cycles Achievement Test ( MCAT) was administered to the students as pre-test, post-test and delayed test. Data obtained via pre-test, post-test and delayed tests were transferred to SPSS 15.00 program; and Wilcoxon Signed Rank test was applied on these data. Frequency and percentage table was constituted. Considering the analysis results, it was concluded that use of worksheets and simulation technique together has positive effects on students' hypothetical, correlation and combinational thinking skills. (c) 2011 Elsevier Ltd.