I have created 8 sets of 10 different problems to help student practice the Distributive Property. After teaching this concept and some practice on it, I will do these speed trials in class. Students love it and after doing several of them they begin to see improvements.
Procedure: Pass out 1 set of 10 problems to each student, making sure that they are faced down and that the students don't try and get a head start by peaking. Also, make sure that each student has the same problems (otherwise it won't work). I usually give my students 1 minute to complete as many as possible. When the time is up, have them exchange papers and check their neighbors work from the answers (I usually have them all prepared ahead of time and put them on the overhead). Probably the most important part of this activity is getting the students to recognize where their mistakes are. They will probably notice that they make the same mistakes.
A lot of times I will do 3 or 4 speed trials a day. You can reuse them on different days because the students will not memorize the answers. In addition to practicing these after it has been taught, you can also bring these out all year to keep their skills good with the distributive property.
Preparing the Activity: I usually will make enough copies for all my students plus 3 or 4 extra copies. To save time, I use a paper cutter and paperclip each set together. I also make a copy of the 2 originals onto overheads and cut them and put them on top of the different sets.