Arithmetic not your kinder's cup of tea? Try tempting him with the elegant simplicity of this puzzle. Numbered wooden puzzle pieces of different lengths interlock and add up to fit on a ten-by-ten grid, but kids needn't worry about doing the mental math. They'll learn through trial and error that the "seven" piece can only fit next to the "three" piece, and this unique toy will help them take the step from experimentation to understanding of basic addition and subtraction concepts. But don't let on that they're learning all that --we wouldn't want to take the fun out of a perfectly pleasant puzzle! (Pottery Barn Kids, $39.00)