Paper Title
Development of Mathematical Connection Skills and Achievement Mathematics on Probability of Mathayomsuksa Five Students by Using GPAS 5 Steps Learning Process.

Abstract
This study aims to develop mathematical connection skills and academic achievement in mathematics before and after learning the topic of probability among Grade 11 students who received instruction through the GPAS 5 STEP learning model. The target group for this research consisted of 40 Grade 11 students from Sarakhampittayakhom School, MahaSarakham Province, during the second semester of the 2024 academic year. The research instruments included Ten lesson plans based on the GPAS 5 STEP model on the topic of probability, with a total learning duration of 10 hours. A mathematical connection skills assessment consisting of five open-ended written response questions. A mathematics achievement test on the topic of probability, comprising 30 multiple-choice questions with five answer choices. The research findings revealed that, when comparing the development of mathematical connection skills and academic achievement in mathematics before and after learning, the post-learning scores were significantly higher than the pre-learning scores at the .05 statistical significance level. Keywords - GPAS 5 STEP learning model, Mathematical connection skills and Academic achievement