Which Numbers Round to 50?

Sixteen numbers sit in a loose staggered field on this 3rd grade page, with a single coral target pill above them reading approximately 50. The numbers on the sheet shown are 31, 46, 36, 55, 49, 44, 63, 51, 47, 45, 35, 58, 52, 64, 57 and 32. The child circles every one that rounds to fifty and leaves the rest. Six of the sixteen qualify. The reference band at the top works a different example, 83 into 80, so the target is not given away twice.

Running the rule backwards is what this face is for. Instead of one number with one answer, the child is given the answer and asked which numbers could have produced it, which is the question that reveals whether rounding is understood as a range or only as a procedure. Both edges of that range are on the page: 45 is in and 44 is out, 54 would be in and 55 is out, so the halfway rule decides two of the sixteen on its own.

One sheet, sixteen numbers, six to circle. Ask afterwards for the smallest and the largest number that would have worked — 45 and 54 — because naming the two ends is the understanding this page is testing. It is the only inverse face in the rounding family and the one to use when the forward pages have become easy.