Oh, and a week ago I got one of those "base ten" interlocking sets (got it used on eBay with couple other fun things). I figured we'd have long ways before we'd ever need it. He found the box yesterday when hubby was watching him, asked what it was ... I showed him how 10 x 10 was 100 and he had 10 of these, told him that was a THOUSAND ... he said "Cool! I didn't know that! Now I know!" and since then he's been using it to build his "creations". I don't think we'll ever use them for math again. So manipulatives might work but they are just a one time thing in many cases so why waste money on them
