One tool that I use to help students review for tests is classmarker.com. I have found that sixth graders don't know how to study for tests. So, I use classmarker as a study guide for students. Before classmarker, I would tell the students to review their notes before a tests. It was as if I had asked them to build a rocketship and fly it to Mars. I would ask my students the next morning, "Did you review your notes last night?" They would always say yes. Then, I would get test grades that were awful. Then came classmarker and its successor, quia.com , to the rescue. My students love taking the online quizes and getting their results right away (not a month later). Quia.com is the upgraded, pay version of classmarker. Quia allows you to create games, tests, and quizzes. My students really like the "Who Wants to Be a Millionaire" spinoff game. I even had a student sign up for a free 30-day teacher account (now he thinks he is a teacher) and create several review games for our class. The best part about classmarker and quia is that I can see who studied last night and who did not by checking my account (no more lying to the teacher in my classroom!). Now, I just have to figure out the disappearing homework thing.
I have created three screencasts that guide you through the processes of using classmarker in your classroom. The first video shows you how to sign up for a free account.
The second video shows you how to create a class and how to assign students to your class.
The third video shows you how to create and manage a test.