This research aimed to 1) develop integrated STEM activities through active learning for enhancing scientific process skills of kindergarten 3 students in a classroom with 30 students, 2) compare scientific process skills before and after implementing the activities, 3) study learning participation behaviors, and 4) examine teachers' and parents' satisfaction. The mixed methods research employed research and development together with a one-group pretest-posttest quasi-experimental design. The samples included 30 kindergarten 3/7 students at Anuban Lampang School, 2 homeroom teachers, and 30 parents. The research instruments consisted of 8 units of integrated STEM activities containing 24 lesson plans, a scientific process skills test, a participation behavior observation form, a satisfaction evaluation form, and a semi-structured interview protocol. The experiment lasted 8 weeks. Data were analyzed using mean, standard deviation, t-test for dependent samples, repeated measures ANOVA, and content analysis. The findings revealed that 1) the developed integrated STEM activities were rated at the highest level of appropriateness (x̄ = 4.68, S.D. = 0.37) and met the efficiency criteria of 80/80 (E1/E2 = 83.45/85.20), 2) students' scientific process skills after the experiment (x̄ = 45.67, S.D. = 3.25) were significantly higher than before the experiment (x̄ = 24.13, S.D. = 4.62) at .01 level, 3) students' overall learning participation behaviors were at a high level (x̄ = 3.42, S.D. = 0.48) and continuously increased from week 1 to week 8 with statistical significance at .01 level, and 4) teachers and parents were satisfied with the activities at the highest level (x̄ = 4.75, S.D. = 0.35 and x̄ = 4.68, S.D. = 0.41 respectively).
Keywords: Scientific Process Skills, Integrated STEM, Active Learning, Kindergarten Children, Large Classroom