Developing Estimation Strategies by Making Connections among Number, Geometry,
Measurement, and Data Concepts: Estimating Cranberries
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 the
second part, Discussing Strategies, the students work in groups to share
their ideas and reach a reasoned consensus about their estimates. In
this third part, Estimating Cranberries, the students estimate the number
of cranberries rather than the number of scoops.Video
Segment
The lesson
continues with the teacher's asking the students to think about how they
would estimate the number of cranberries in the jar. The groups work to
determine a value that represents the number of cranberries in a scoop
and how to use that value to estimate the number of cranberries in a jar.
The class comes back together, and each group shares its value for the
number of cranberries in a scoop. These values range from twenty-one to
twenty-eight cranberries per scoop. In this last video segment, the students
talk about how and why they have come up with different values for the
number of cranberries in a scoop and what single value the whole class
might use as the number of cranberries in a scoop.
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Discussion
Teachers
can help students develop estimation skills by planning slightly varied
versions of activities, so that students are likely to recognize that
strategies that were successful in one situation may be helpful in the
new tasks.
The
discussion of an average number of cranberries in a scoop ends with
the selection of a value of twenty-five. The teacher then relates the
counting of multiple scoops to the skip-counting used when counting
quarters to add up to a dollar. The class uses this counting technique
to determine that it takes approximately 300 cranberries to fill a jar.
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Take
Time to Reflect
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- What
mathematical ideas from number, geometry, measurement, and
data do the students use to complete the activities in this
lesson?
- How
does the teacher encourage the students to make mathematical
connections?
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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.
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