Estimating Scoops

  • 4.6.1 Estimating Scoops

    Grade: PreK to 2nd

    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.


    ----- Transcript Begins ------
    Teacher: Please ask your group person, that has their paper and pen, for a piece of paper so that you can write down your estimate. Now remember, it is not how many cranberries are there in all, it is how many scoops. That is different. A lot of times we count how many in all; right now, we are interested in how many scoops it would take.
    ------ Transcript Ends -----


    Video Segments

    The class in these video segments is engaged in the estimation and analysis of data centered first on the number of scoops of cranberries to fill a jar and then on the number of cranberries to fill the jar. In this segment, each student makes an estimate of the number of scoops and then the class organizes their collective estimates in a meaningful way.
    Consider what mathematical concepts these students are using. How is their thinking encouraged, and how else could it be encouraged?
    Teachers plan lessons, encourage working groups, and guide class discussions, all of which influence the extent to which students are likely to make connections among the many mathematical concepts they are learning. Throughout this video example, the teacher talks about her decisions as the students are making estimates and collecting and interpreting data. What do you notice about how the teacher interacts with the students in the activity?



    Keeping each student's attention during whole-group discussions is often difficult in prekindergarten through grade 2 classrooms unless the students are involved in the activity. The teacher of the second-grade class shown in the video is using locally grown cranberries as a physical material for helping students develop estimation skills. The activity involves much more than students' looking at a jar of cranberries and a scoop to make their estimates. The teacher helps the students examine their estimates using the graph they create. Then (not shown in these video clips) the teacher and students discuss the range of responses (from 5 to 22) and the mode, the number named most frequently. In this way, she takes advantage of a teachable moment to introduce the concept of mode.

    Take Time to Reflect 

    • What do you observe about the students in this brief video that might influence the decisions the teacher makes as she introduces this lesson?
    • How does the process for creating a graph shown in the video facilitate the students' understanding of their data?
    • In what ways does the teacher involve all students?

    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.

    Objectives and Standards

    NCTM Standards and Expectations
    • Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.
    • Apply geometric concepts in modeling situations
    • Pre-K - 2
    • Data Analysis and Probability
    • Number and Operations