I can't remember for elementary, but probably less than an hour/day. High school was about an hour a day.

Undergrad at uni, 2-3 hours a day. Law school averages 4-5 hours a day or more, including the frenzied month right before the end of term, in which it is not uncommon to spend 60 hours a week working outside of class. I'd say it takes 2 hours a day just for the readings, and the additional time is for research papers and/or exam prep.