As I mentioned in my last post,  number talks lately have felt a little off in my classroom.  My new student has changed our classroom dynamic a little bit, and I don’t feel that I’ve been doing a good job choosing problems that are accessible for all my students.

So for today’s number talk I revisited addition–specifically a problem that uses the “round and adjust” strategy mentioned in “Making Number Talks Matter”.  Previous units have worked on both rounding and addition and (to me) it seemed like a very natural strategy when adding -9 numbers.

So here was my plan, including a few expected student strategies:

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And here are the results! You can see that I’m not super great at predicting the strategies my students will use, and absolutely 0 of them volunteered the strategy I was aiming for of “round and adjust.  I always really love listening to them and their explanations though.

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A few strategies I’d like to highlight:

-S has been a really reluctant participant in number talks this year (this was his first time to share a strategy!) and I was incredibly pleased that he volunteered to share his thinking with us.  He started by finding the double 9 +9 in the problem, and then added on the 4 he took from 13 to make the second 9.  He clearly articulated his thinking to the class and was even able to take on some questions.  A few students were unsure of where he got the 4 from that he added on to the 18.  Having another student re-explain his strategy was a great teaching moment for the class.

-My strategy! After seeing that none of my students had used the strategy that I was aiming for, I decided to speak up and offer another way of seeing the problem.  I’m so glad that I did! As soon as I said “Well, I knew that 9 was really close to 10…” many kids piped up and said “You rounded!”.  After going through the rest of my idea, one student had a question for me about why I needed to subtract the 1 after I had added on 10.  We spent a few minutes discussing where that -1 came from and I feel that at the end of our conversation he was a little more clear about it.

Overall I was really satisfied with our number talk today.  I had many students anxious to participate with accurate strategies, which tells me I did a better job picking an accessible problem. So where do I go from here? I think that I definitely want to try out another addition problem tomorrow that lends itself to “round and adjust”.  I am anxious to see if my student who questioned me about it today is able to try it out on his own tomorrow.