Whenever I want to assign practice problems during class, my students will usually ask if it is a graded assignment.  I don't want to spend the time grading a set of practice problems, I just want them to practice what I just taught them.  The problem is, if I tell them it is not graded, most of my students will put little to no effort into this assignment.  Have any other teachers experienced this?  Other then taking the time to grade each practice, how have you overcome this?