Prapaporn Nongharnpituk และ Manad Suranna; Paweena Khansila. (2023) The development of problem-solving ability on addition and subtraction of Garde-4 students using Polya's problem solving process with Bar model. <i>Journal of Science and Science Education</i>, <i>6</i>(2), 269-279.Prapaporn Nongharnpituk และ Manad Suranna; Paweena Khansila. "The development of problem-solving ability on addition and subtraction of Garde-4 students using Polya's problem solving process with Bar model". Journal of Science and Science Education 6 (2023):269-279.Prapaporn Nongharnpituk และ Manad Suranna; Paweena Khansila. The development of problem-solving ability on addition and subtraction of Garde-4 students using Polya's problem solving process with Bar model. Faculty of Science, Ubon Ratchathani University:ม.ป.ท. 2023.