Solving online puzzles, riddles, and brainteasers are a great way to increase reasoning and problem solving. Discussing the problem and possible solutions boosts your brainpower and expressive language skills. Here are a few of Mrs. DeYoung's favorite brainteaser websites:
http://school.discoveryeducation.com/brainboosters/
http://kids.niehs.nih.gov/braint.htm
http://www.mindbreakers.com/
http://kids.mysterynet.com/