Goal: Think like a mathematician! Find a calculation shortcut by chunking, changing the form and connecting to math you know.
CthenC Google Slides Multiplication Shortcut #3
CthenC Planner Multiplication Shortcut #3
CthenC Meta Reflection Multiplication Shortcut #3
Back to Contemplate then Calculate Tasks
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We used this task in my seventh-grade classroom. Last year we did Number Talks, and this seemed like a more structured way to accomplish something similar.
What was interesting about the CthenC structure with this problem was that students could remember and try to solve the problem during the noticing phase. We had to really encourage them to try to notice things that could help them solve the problem. A couple of students noticed that 29 is close to 30 or that 5 is half of 10, or even that 29 is 20 + 9, but many students struggled to slow themselves down enough for the noticing.
This was only the third time we had done the routine, so I’m interested to see if they get better at single operation-type problems as we use the routine more.
Hi! I am doing this routine with an elementary staff, using this equation. The staff is wanting to start using equations and move from dots, and is needing some support in that. I am curious what other people got for things people noticed. So far I have that the 29 is close to 30. That five is a friendly number or half of 10. You can decompose the 29 into 20 + 9 or 25 (quarters) + 4. Anything I’m missing? Thanks!
Hi Marlana,
You have a pretty extensive list of potential noticings! With adults, they may also notice that 29 is close to 25.
Every shortcut opens up a productive conversation about mathematical structure. Please update us re: how it goes!