I use these leveled practice worksheets by posting the answer keys in stations around the room. Students start at the easiest level, check their answers when finished, then move on to the next level. The fourth level is an extension, introducing more advanced concepts to students who move quickly through the practice. I circulate, helping students who I see are working more slowly or struggling.
I plan to add the answer sheets soon, so check back if you need that, though I think it's really valuable to solve them yourself!