Content area
This study used the APOS theoretical framework to assess secondary school pupils’ set math knowledge. Princess Chulabhorn Science College Lopburi randomly sampled 20 8th graders in the second semester of 2022. There are a total of six plans, with each plan comprising a 180-minute. The objectives are the instructional goals. Content is the topic. Learning materials include resources and tools. Last, activities include learning assignments and exercises. Assessment includes three subtests to assess set understanding and a test to assess mathematical comprehension. These activities increased secondary school students’ set comprehension. The result of the study indicated that they had demonstrated a strongconceptual understanding of set theory to pass the criteria over 60% of the total students with a statistical significance level of .01. Furthermore, delving into all four APOS theoretical levels we found similar impressive results, with over 60% of students exceeding expectations at each level (p<0.01).