This week there are 4 warm-ups; we had a special parent visit on Friday morning and so didn’t get to one that day. We’re still working on addition/subtraction and using efficient strategies.
The hope with the numbers in this problem was that kiddos would recognize the most efficient strategy was to use compensation (and so make the easier problem of 30+61 that they could answer in their heads), but any strategy was fine as long as they could pick one and explain it.
The other day, we discussed all the strategies we know how to use and tried them on the same problem. We also talked about what we could call them so that everyone knows what we’re talking about (this was in response to a question I asked last week with our warm-ups). So I decided that we’d try a specific strategy on a series of problems this week (but it should be noted that, as with the last problem, compensation is the BEST strategy for the numbers as you can create 81+20 and quickly answer using mental math).
Besides talking about how to accurately use the strategy, we had a discussion about the difference between how you solve the problem (the strategy) and how you SHOW how you solved it (the model–in this case an open number line).
The thinking behind this problem is helping kiddos connect strategies they know for ADDITION with SUBTRACTION. Many first graders need to be explicitly shown that what works for one works for the other. Practicing using these known strategies can help stretch some past the draw-all-then-mark-off or counting backwards strategies.
These warm-ups got kiddos’ brains really moving this week! Hope they work well for yours, too! Please leave a note and tell us about how you’re using them in your classroom, or how you’re sharing them with others. 🙂