Marginal effects

brms allows one to plot marginal effects

For standard linear models this is useful for group comparisons and interactions

For nonlinear models (glm and beyond) useful for any effect

marginal_effects(attendance_brms)

These are ggplot objects, so you can modify them accordingly

math_me = marginal_effects(attendance_brms, effects = 'math')
plot(math_me, 
     plot = F,
     rug = T,
     rug_args = list(color='darkred'), 
     points = T,
     point_args = list(color='papayawhip'))[[1]] +
  theme_black()

Example with smooth interaction

attendance_brms_inter = update(attendance_brms,  ~ . - math + s(math, by=gender), cores=4)

marginal_smooths(attendance_brms_inter)