Join Mrs. Gray for a Mystery Math Mistake with D.C. He needs your help with his number bonds. We will be counting pictures with ten and some more to answer the question "how many?" Episode ...

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Help D.C. with number sentences and ten frames, then learn about groups of up to 20. Join Mrs. Gray for a Mystery Math Mistake with D.C. He needs help figuring out his number sentences to match ten ...

A version of this puzzle originally appeared in the October 1960 issue of Scientific American. What’s the Most Distant Galaxy ...