Mastering Mathematics Work-Textbook Secondary 3A is developed from the most renowned mathematics series for secondary levels in Singapore based on Thailand’s newly revised curriculum of B.E. 2560(A.D. 2017). It includes various active learning activities to help increase students’ knowledge and enhance their thinking skills. It also provides marginal notes along the way allowing students to extend and increase their understanding on what they have learned. Finishing with Problems in Real-World Context, it allows students apply their mathematical knowledge on real-life situations.