Does graded homework improve students (across multiple subjects) or is it just a sub-optimization?
If a student is given more graded homework in Physics, then they won't do as much ungraded homework in Biology (especially if the grades go towards their final marks). So do students learn more by doing graded homework, or is it just a turf war between different teachers all trying to push kids to work harder in their subjects?
Also, does homework discourage students from doing extra-curricular activities (i.e. learning things for themselves)?