The Study of Mathematical Problem-Solving Ability and Teamwork of First Year Vocational Certification Students of Surface Area and Volume through Problem-Based Learning.

a statistical significance level of .05. ln addition, the teamwork of the students overall was at the
very good level. The student’s teamwork scores in each lesson plan were at good to very good
levels.The purposes of this research were: 1) to compare the mathematical problem-solving ability on the
topic of the surface area and volume before and after learning management by using Problem-Based
Learning (PBL) for first-year vocational certificate students, 2) to compare the mathematical
problem-solving ability on the topic of the surface area and volume by using PBL for first-year
vocational certificate students compared to the criteria of 70 percent, and 3) to study teamwork of
first-year vocational certificate students after learning management by using PBL. The sample
group for this study comprised 29 first-year vocational certificate students in Food and Nutrition
Major, Chitralada Vocational School who were studying in the second semester of academic year
2023. They were selected by using the purposive sampling. The research instruments included five
lesson plans using PBL and the pre-test and post-test with five items in the mathematical problemsolving ability. The data were statistically analyzed by mean, standard deviation and t-test. The
results showed that the students' learning achievement of the mathematical problem-solving ability
on the topic of the surface area and volume by using PBL was higher than before studying at a
statistical significance level of .05. The academic achievement was higher than the 70% threshold at