Especially for secondary students, staying after school for a supervised study time is often one of the most effective options. Some system to trigger after-school study detention is helpful, such as following a specified number of incomplete assignments. The need for separate transportation home typically adds a bit of gravity to the issues. Also, the student is more likely to have a quiet, extended time to really focus on the work, presumably while the teacher is also working quietly on lesson prep. This arrangement also provides a setting for the teacher to help the student if the issue involves difficulty in understanding how to do the work. You do need to have parental support for all this.