Is boys' superiority in science learning a myth or a reality? On this question, different researchers give different answers. However, it is still an interesting and important question to explore.We were eager to explore the gender differences between boys and girls in science performance in China. If gender differences do not exist, then educators should discard their belief about boys' superiority. On the contrary, if there are significant gender differences in learning science, then the education profession has a direct responsibility to enable boys and girls to fulfill equally their cognitive potential in science.In this study, we explored the gender differences between boys and girls in science performance in China. The data we used were collected from the Chinese National Assessment of Education Quality (CNAEQ), which was launched by the Collaborative Innovation Center of Assessment for Basic Education Quality with authorization from the Ministry of Education of the People's Republic of China. The CNAEQ is China's largest continuing and nationally representative education quality assessment which started in 2015 and covers six essential disciplines including language, mathematics, science, art, physical education and health, and civics. The assessment schedule is conducted across a 3-year period with two disciplines every year (Wu et al., 2019). In the science assessment of CNAEQ, students' science achievement, science interest, learning habit, and creativity were investigated, which provided us a high-quality source to explore the gender differences in China. LITERATURE REVIEWThere are numerous quantitative studies on the performance of boys and girls in different subjects. The performance compared in studies contains academic achievement, learning attitudes, and emotions, such as learning interests, habits, and creativity, which are all considered as important factors of academic performance nowadays. Different subjects as well as different item forms are also investigated in different researches. The gender gaps over time also attract researchers' interest.In academic achievement, many studies investigated the academic gender gaps, most found that boys outperform girl in science, and the gaps are larger than mathematics. It has been reported that boys are significantly better than girls in biology, introduction to science, and physics (Becker, 1989; Steinkamp and Maehr, 1983), while girls are superior in language ability (Halpern et al., 2007). Furthermore, gender effect sizes (ESs) for science were found to be somewhat larger than those for

This study aimed to investigate the features of only child status related to physical health, mathematics achievement, and school feelings and expectations from a different perspective. A representative sample of 91,619 Grade 4 students with an average age of 10.4 ± 0.7, among which 28,631 were only children, were assessed. We used propensity score matching (PSM) and the average treatment effects on the treatment to analyze data. The treatment was the only child of a family. The results indicated that only children have better academic achievement and school feelings (only for urban only child girls), while non-only children have better physical status and anaerobic fitness (AF). In addition, gender and rural vs. urban areas differences were also explored. The adverse situation for rural only boys is emphasized for families, researchers, and governments to focus on. Some suggestions are given under the Two- and Three-Child Policy.