The purposes of this research were: 1) to develop and find the effectiveness of an instructional package on counting numbers, addition, subtraction, multiplication and divistion for Prathomsuksa 6 students using the Team Assisted Individualization (TAI) technique to meet the criteria of 75/75, 2) to compare the learning achievement of students using the instructional package before and after instruction, 3) to measure students’ satisfaction toward the instructional package. The population of this study were 552 Prathomsuka 6 students at Sarididet School in the first semester of academic year 2016. The sample of 49 students was selected by simple random sampling. The research instruments used were: the instructional package, a learning activities lesson plan, a pretest and posttest, and a questionnaire concerning students’ satisfaction with the instructional package. The statistics used for analyzing the collected data were: mean, standard deviation, and t-test.
The findings were as follows: 1) the effectiveness of the instructional package had an efficiency of 78.27/82.72, which was higher than the criteria of 75/75, 2) the learning achievement of the students using the instructional package, as measured by pretest and posttest, increased in all aspects at the statistically significant level of .05, 3) students’ satisfaction with the instructional package was at a high level and had a mean score of 4.46 out of 5.