I made index cards with numbers 0-10 (underlined), and put the same #
of stickers on the other side. I pulled 10 large white buttons from my
button jar, and the idea is for D to see a #, and count out that many
buttons, then check his work by covering the stickers on the other
side. I tried to arrange the stickers so that he'll memorize the
grouping to make life easier later. (so 9 are lai out 3×3, 7 is a row
of 3, with the other 4 staggered below, etc)