A lunch discussion on beauty premiums in school led me to dig this up. As I read it, one SD (.72) in attractiveness is associated with a .4 increase in grade point (from 6 to 1) in math exams and 1.3 points in arts/music/literature. 10 and 15 year olds.
https://www.degruyter.com/document/doi/10.1515/zfsoz-2012-0206/html
though I had to update on one thing: I thought the effect would be bigger for girls, because of some not-so-fond memories of male teachers at my high school. not the case here.
thanks to @TaymAlsalti for a potential explanation
https://youtu.be/10Jp5SiBezQ
correction: I misread the part about a larger effect in arts/music/literature. afaict, they didn't test that and I wished too hard that they did. effect sizes make more sense now.
thanks @Scientific_Bird
I thought there would be an effect, but the effect size surprised me! It's half as large as the IQ effect and if you compare the least to most attractive, the differences beat sex, migration background and parental education (yeah Table 2 fallacy, I know I know).