Number Talks to Get Students Thinking Number Sense

I recently read Number Talks by Sherry Parrish. I thought I would give Number Talks a try to ramp up my fourth graders thinking with multiplication. Like many students, once they learn the algorithm, boom, it becomes a rote, automatic process. But my question my students really understand the conceptual meaning of what it means to multiply and what the process really represents?

A Number Talk should take no more than 15 minutes. The ultimate goal is not the answer, it is the processes used. Yes, I said processes, multiple representations. Students are asked to solve the problem using mental paper pencil. Put those pencils down and get those thinking caps on! Once students are able to determine the answer, they give a silent "thumbs up." It does not stop there. Students are encouraged to come up with other ways to solve the problem. When they determine another process, they put up another finger. Are you beginning to see how process is the focus. The silent "thumbs up" gives all students a fair chance to solve the problem while challenging those fast finishers to keep thinking.

The first problem we worked on was 25 x 7. I showed students the problem written horizontally. Remember no paper pencil is allowed. It was silent in the room, and then thumbs started to pop up. After a few minutes, everyone at least had their thumbs up. I asked students to share their answers. At this point, all answers are recorded and respected. Through discussion answers are confirmed, defended, or rejected. Students then went on to share the processes they used to solve the problem. One student explained that  20 x 7 = 140 and 5 x 7 = 35. Then the student went on to add 140 and 35 to get the answer of 175. Another process showed that 4 x 25 = 100. When doubled, it would be 200, but then 25 had to be subtracted because there were only 7 25s and not 8.

We then went on to 12 x 15 written horizontally. Now remember students are encouraged to think and solve using mental math. I will keep the examples short here. One student said he took (12 x 5) + (12 x 5) + (12 x 5) = 180. WOW! When I asked the other students why he did this, they chimed in, "Well, he broke down 15 into three 5s." Why 5s? "It is easier to multiply by. It is like a benchmark," they added. This was the first time my students engaged in a Number Talk. Conceptual understanding of number sense was definitely shown here. Give a Number Talk a try and see the different strategies students can use to a solve problem. Model and guide students to new ways of approaching problems to build their understanding of number sense and various processes. Manipulate and play with numbers to solidify understanding.
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