For those kids that like math and wish to boost their skills while having fun solving puzzles, here's a good site. It covers math from 1st grade through 6th grade as well as algebra.

http://www.mathsisfun.com/puzzles/

The specific category of puzzles are

starter, measuring, logic, shape, number, algebra, assorted math puzzles and quizzes, card, tricky, Einstein, Sam Loyd, symmetry jigsaw, puzzle games

Give them a shot and have fun!