This study aimed to determine the gender differences in terms of their learning and educational opportunities particularly on male students in Thailand. Researchers searched for the fundamental aspects of gender bias in educational opportunities from different points of view. Researchers gathered 54 related past studies to investigate the three major gender aspects namely factors that contributing to classroom learning, internal factors within the learners, and other surrounding factors. Content analysis and meta-analysis techniques were employed as systematic researching strategies. According to the results derived from past studies and in-depth interview with experts as well as focus group interviews with male students indicated that there were at least 12 variables that related to the male students' poor learning achievement. These 12 identified variables are ethical behavior, learning skills, attitude towards learning, learning behavior, aggressive behavior, learning hindrance, self-perception, nature or sex drive, social environment, attitude towards sexual relationships, learning ability, and expectation for furthering education. The findings demonstrated the constructive results to the public, educators, and policy makers with an understanding of the gender equality phenomenon in educational opportunities and could facilitate us to perceive the background of the phenomenon so that the solutions for solving traditional practices can be challenged.