I was in a training today and they had us solve a Van de Walle problem called One Up, One Down. It goes like this:
When you add 7 + 7, you get 14. When you make the first number 1 more and the second number 1 less, you get the same answer. (Van de Walle, Karp, and Bay-Williams, 2013, pg 17)
Our challenge was to determine if this would always work for doubles and if it would work for situations where the addends are not the same. We had to have a representation to show our thinking. The different representations that people came up with were very cool! Here are a few…
|A ten-frame representation
|Using counters as a model
|An addition/subtraction chart
|Yikes! Big math!
Awesome activity, don’t you think? Enjoy your weekend!