My Take
Sumdog is a great way for kids to practice their math facts. The free version allows students to play games whose scores are based on the amount of math problems answered correctly. Students really love this site. They enjoy playing against each other in the Class mode. The many regional contests are a big motivator as well and have had many of our students win or place in the top ten in the entire state!
How I Use It
Students often ask to go to this site and I use it as an award for good behavior and well done class work. It is like electronic flash cards with a bonus. Sumdog keeps track of problem areas and reinforces the student's learning until the math fact is mastered, even with the free subscription. It is one of the few sites that allows students to play each other even from their homes. Great site!