This paper explores the impact of a tailored working memory training program on the mathematics achievement of secondary school students in Myanmar. While previous studies have investigated the relationship between working memory and mathematics, this study focuses on a context where computerized training programs are limited. Twelve Grade 8 students participated in a six-week program conducted via Zoom due to the pandemic. A Mathematics Achievement Test, aligned with the curriculum, assessed their performance before and after the program. Semi-structured interviews were conducted to gather insights into the students' experiences. Results showed significant improvements in mathematics achievement, particularly in geometry, after the training program. Working memory strategies such as chunking, visualization, and concentration were found to enhance problem-solving abilities. This study highlights the potential of working memory techniques for enhancing mathematics education, particularly in areas with limited technology access.