In this Number Talk, the students are working on strategies for mentally adding and subtracting within 100. They demonstrate fluency with the operations through their ability to perform the operations mentally and share their thinking with partners and as a whole class. This lesson strongly exhibits all three Core Actions.
Number Talks (Waldron)Download
In this part of the lesson, the students are sharing their answer, the strategy they used, and how they solved the problem with a partner at their table. The female student in the video can be observed changing her answer from 94 to 96 as a result of talking through the math and explaining how she got her answer.
Here, three students share their strategies to how they solved the problem mentally. The first student invents her own strategy, called "splitting addition." She demonstrates how she splits the numbers and talks through each step. The second student who goes up uses place value as his strategy. He also talks through his steps. The third student uses "splitting" as his strategy. He splits 48 into 40 and 8. He adds 8 + 8 = 16, 40 + 40 = 80, and 80 + 16 = 96. Each student who shares asks the rest of the class if they agree or disagree.
In this part of the number talk, the teacher is sharing the number story aloud with the students. She shares it orally and writes the numbers on the board (26 and 64). Students ask clarifying questions before and during think time and students can be observed showing they're ready with an answer by holding up their thumb over their heart. A students at the front table can be observed using a whiteboard to solve the problem and the teacher checks in with her to make sure the numbers are lined up correctly. All students are employing a "tool" through the strategy they choose to solve the problem. Students are demonstrating fluency with adding numbers within 100 by solving this problem mentally.
The teacher poses three high quality questions for the students to discuss with partners orally and posts them on the board: "What did you get?", "What strategy did you use?", and "Explain how you solved it." She then goes over to a partnership and listens in to the conversation, checking for understanding.
Here, a student is sharing how she solved the problem. She demonstrates how she used a number line and "splitting." She makes "jumps" on the number line to show how she arrived at her answer. The second student uses "split-ation" which is splitting + compensation. He demonstrates how he used a combination of those two strategies to solve the problem. Having students demonstrate their different solution methods strengthens the other students' understanding.