I am a middle school science teacher, and I use Quia on a daily basis in my classroom. I don't use much software, just online services. This is the only one I like well enough to pay for. I use the activities to add extra 'fun' review. I use the quizzes for assessment, and I use the surveys to gather information about how to make my class better. I believe it always increases learning!
Ty Newton, middle school science teacher, Gig Harbor, Washington, U.S.A.