Also, I love that students get instant feedback on how they are doing and explanations of what they did incorrectly before they move on.
When I used worksheets as homework, students would sometimes complete an entire assignment incorrectly—now they can't do that, as IXL doesn't allow their Smart Score to increase unless they are getting problems correct. For monitoring progress in class, I love the Real-Time Center.
The leaderboard changes so much that I generally have a different top and bottom [student] every time I post an update. I put the students score on the screen with my projector. When it is possible, I teach a lesson in math or language arts, and use IXL as practice work.
If a student has trouble and their box turns [red], we call out, "Who ya gonna call? I have seen an improvement in my students after using IXL.
In the honors setting, the competitive spirit is high and some kids really like trying to be the one with the most topics mastered or the highest Smart Score gained in a week.
Even those who don't thrive on competition, the open sharing of how much everyone has done allows them to see how they're keeping pace with their peers.
After teaching a new concept and working through some sample problems together...
After teaching a new concept and working through some sample problems together as a class, I assign related lessons on IXL for my students to complete in class.
Students who completed a certain amount of IXL skills were invited. At the end of the year, they were so motivated to beat the high score, they would do extra IXL skills during their free time.
I use IXL in my Honors Algebra class as a replacement for most in-class worksheets and homework, as our school has a 1-1 i Pad initiative.