I go to school full time and volunteer part time, so I know what you mean. I think everyone here has the right idea, spend as much time as you can and don't feel like a bad mommy. I get up early (even on weekends) and take Kiwi to the park or another fun place for at least an hour. We have so much fun together! Then she is ready to take a nap and when she wants to play again is about the time I need a break from homework, so we take a short walk or play or something. Although you are play with her to exercise her, she sees it as fun time with you, so don't feel guilty!