Abstract

The study adopted quasi-experimental of pretest posttest non-equivalent control group design. The population of the study comprised all Chemistry students in all (40) secondary school in Niger State, Nigeria. The target population for this study consisted of all senior secondary school two (SSII) Chemistry students in forty (40) school with a total number of two thousand three hundred (2300) Chemistry students, comprising 1300 males and 1000 females. Simple random sampling technique was use to select two schools from the population. The two schools were selected using balloting. One hundred (101) senior secondary school two (SSII) Chemistry students were sampled comprising forty eight (49) males and fifty two (52) females and took part in the study. A fifty (50) items Chemistry Critical Thinking Skills Test (CCTST) was used for data collection in this study. CCCTST was validated by two senior lecturers. The reliability of the Chemistry Critical Thinking Skills Test (CCTST) was established using split-half reliability method and the coefficient was calculated using Spearman Brown's Formula and it was found to be 0.781. Mean and standard deviation were used to answer the research question while the hypotheses were tested at 0.05 significance level using ztest for independent sample. The findings from the study indicated that there was significant difference in the mean critical thinking skills between students taught Chemistry using graphic organizer and those taugh using Lecture method in favor of experimental group. It was concludes that Students taught chemistry using graphic organizer possess higher critical thinking skills than their counterpart students taught using lecture method. As such graphic organizer increases the level of students' critical thinking skills. On the basis of this findings, it was recommended among others that secondary school Chemistry teachers in Niger State, Nigeria should employ the use of graphic organizer as a teaching strategy to enhance critical thinking skills of students.