Sumdog adapts its questions to each student's ability, so every student has a good chance of winning.
Because students will answer questions targeted to their abilities, you don't need to worry about your contest team being comprised of mixed ages.
To make contests fair for students with limited access to computers, every student is limited to 1000 questions. However, it's fun to take part even if students only answer a few questions.
The class score is calculated as the class average rather than accumulated correct answers.