Abstract The objectives of this research were: 1) to develop self-learning package for teachers titled “Students’ Thinking Skill Assessment,” with efficiency 80/80, 2) to find the effectiveness index, 3) to compare the pretest and posttest scores between before after studying selflearning package for teachers titled “Students’ Thinking Skill Assessment.” The samples using in this study were 60 teachers under jurisdiction of the Office of Mahasarakham Primary Educational Service Area 1, 2011 school year. They were selected by... more