Research has been unable to prove that homework improves student performance in elementary students. Instead, I ask that you spend your evenings doing things that are proven to correlate with student success; eat dinner as a family, read together, play outside, play a board game and put your student to bed early. 
The only homework that I typically ask for is to read; the best way to be a better reader is to read! Yes, even for math!  Improvement in reading has been proven to increase student performance in all content areas.