Sumdog.com is a great site for students to practice their math facts. From their website, we read, "All of Sumdog's games are free to use at home or in school (why is this?). Each one covers 100 numeracy topics across 10 levels, and most are multiplayer - letting you play with other students around the world.
Students can sign up free to customise their profile picture and track their individual progress.
Teachers can sign up free to set up their school, create free student logins, see students' activity in the last week, and set up multiplication competitions."
It does appear that if you don't pay for the service, you can setup your whole class, print out cards for them to access their accounts and see how many problems they solve, but they can not compete within the class. I actually think that is good as I don't really need for my students to be more competitive with each other, I do want them to be more focused on improving their own skills. The level of skill is easily set by the player. I think that the students will choose to play this.
I recommend you looking into this.
