None at all. Assigning homework is something I rarely do, but when I do, it's because I am giving them an idea of what to do to reinforce what goes on during my class that they can't do in my classroom, assuming they want to do it. My students have their own lives to live, and assigning homework assumes that they have nothing scheduled once the last bell rings and the school day is over. I will let them know what is going to be taught in the next class so they can prepare, if they have the time or inclination, but it's not really necessary as I introduce the subject matter at the beginning of the class anyway. I think the same idea translates to elementary school children. Their parents assume responsibility for them once they are out of the teacher's hair, and then it is up to the parents to be parents. They might have their own ideas, and that has to take precedence over my ideas. I'm not their parent. I'm just their teacher.