The article examined the effectiveness of using summative evaluation in developing a deep understanding and critical thinking skills among secondary school students. Preparing questions which contain an explanation of concepts in the question paper helps the students to develop a deep understanding and critical thinking skills while answering. The answers of the students were analyzed both quantitatively and qualitatively. The researchers identified five themes based on Bloom's theory of cognitive taxonomy to explore the critical thinking skills of the respondents. There were five components: comprehension, application, analysis, synthesis, and evaluation. Content analysis indicated that the above method limits the confirmation bias. A comparison of answers to three tests in history showed a significant difference (p < 0.01) between the control group (N = 151) and experimental group students (N = 129). Adding positive or negative content in the description of concepts in the essay question influences the response.