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Developing Estimation Strategies by Making Connections among Number, Geometry, Measurement, and Data Concepts: Discussing Strategies


Discussing Strategies

Estimation activities encourage students to make connections among the mathematics concepts they are learning and the skills they are developing. In this multipart video example, the class discussions and the decisions the teacher makes contribute to students' opportunities to connect their understandings of number, measurement, geometry, and data in order to make estimates. Purposeful activities together with skillful questioning by the teacher can help students understand relationships among mathematical ideas, as described in the Connections Standard. In the first part, Estimating Scoops, the teacher presents an estimation task (estimate the number of scoops of cranberries in a jar) to the second-grade students and talks about the teaching decisions she is making. In this second part, Discussing Strategies, the students work in groups to share their ideas and reach a reasoned consensus about their estimates. In the third part, Estimating Cranberries, the students estimate the number of cranberries rather than the number of scoops.

Video Segment

In a section of the lesson preceding this video clip, the following occurs: the teacher has one student place three scoops of cranberries in the glass jar while another student tallies the number of scoops. Many in the class, on seeing the benchmark of three scoops, want to change their estimate of the total number of scoops to fill the jar. The teacher gives each group an identical jar already containing three scoops. She directs the groups to come up with a single estimate and an explanation of how they thought about the situation.

In this second video segment, a group of students is working to analyze the situation, revise their initial ideas, and decide on their group's estimate. Observe the teacher's discussion of the strategies used by the students. What mathematical ideas are emerging?

 

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Video Transcript
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Discussion

For students to function effectively in groups, the teacher must take care to be very clear about his or her expectations for how students will work together. Reaching a consensus requires that all students have an opportunity to tell their ideas and then negotiate with the others to arrive at a group answer that the group members can all justify. In the video, the teacher asks different students in the same group questions to guide them in clarifying and adjusting their estimates and in considering alternatives.

Following the small-group work, the class comes back together with their revised estimates. The estimates range from nine and one-half to thirteen and one-half scoops. The teacher points out that the range has narrowed significantly from the original estimates, which ranged from five to twenty-two scoops. Each group fills its jar and records the number of scoops. The range for the actual number of scoops is from ten and one-half to thirteen and one-half. The teacher facilitates a discussion comparing the sets of data and notes how the use of the benchmark has made the group's estimates much closer to the actual counts.

Take Time to Reflect
  • In what ways does the teacher help her students build new ideas on what they already know?

  • How does the teacher's strategy of moving from the whole group to small groups facilitate participation by all students?

  • Also consider this video segment in which the teacher discusses the participation of a student with Down's Syndrome.


Video Credit

Roche, Robert . "Cranberry Estimation." In Estimating produced by WGBH Boston. Teaching Math, A Video Library, K–4. Funded and distributed by the Annenberg/CPB Math and Science Project, P.O. Box 2345, S. Burlington, VT 05407-2345, 1-800-LEARNER.


Discussing Strategies

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