Grade
3

Same & Different: Shelly's Seashells

Look at the two pictures. What do you notice?

A: A shell is measured on a number line marked in thirds from 0 to 1. The shell measures 2-thirds of a unit long. B: Two shells measured on a number line marked in sixths. The first measures from 0 to 2-sixths of a unit long. The second measures from 2-sixths to 4-sixths of a unit long.
  1. How are pictures A and B mathematically the same, and how are they different?
    • A and B are the same because …
    • A and B are different because …
  2. Make a third picture that shows the length of something less than 1 unit long. Explain how your picture is the same as pictures A and B, and how it is different.
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Reference for Educators

Sample problems and solutions