chose this distance between knots to match the length of the blue whole strip they each had and the magnetic whole strip i had.
i talked with the class about how knotted strings were used as early measuring tools, before we had rulers and tape measures. i taped the string on the board and asked them to think about it as a number line. i labeled the knots 0, 1, 2, and 3.
we checked with the red 1/2 strip to confirm. when i asked them how i could label this point, they said it was 1/2. i wrote 1/2 on the board under the point..
then i did the same to locate 