When my son is set homework I make him sit at the kitchen table for at 20 minutes minutes and I set a cooker timer. I will let him get up from the table earlier if he has completed the work to my satisfaction. He is allowed to ask for help, but I like him to least make an attempt. My son is in year 2, and is usually very good about doing homework, once he has got started.
I make sure he goes to the loo first and if he gets up from the table before the cooker timer goes off or before I say so then he is in trouble. He only gets numeracy and literacy homework once a week. I also look through it to see how much parental input is required.
Anyway he has been role playing with his teddies and saying in a very stern voice. "If you get up from table before this is completed then there is no TV or computer for you." He's scary and I think if I was teddy I would be quaking.