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

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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 ...

Students in Melissa Williams' kindergarten class at the Westminster School in Atlanta, Georgia, practice connecting quantities to written numbers — a key part of number sense. Credit: Holly Korbey for ...