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### Info

3-6,13+

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## Estimation

Students practice their estimation skills by estimating time and numbers of objects in situations in which counting is not feasible or necessary.

### Overview

Students are asked to estimate time and numbers of objects in situations in which counting is not feasible or necessary. This CYBERCHASE activity is motivated by two sections of a Cyberchase episode: 1) In the For Real section, Harry is waiting in line for tickets and trying to estimate whether he has enough time to buy his tickets before the booth closes (based on the length of the line and the rate at which it is moving); and 2) In the animated portion of the same episode, Inez estimates whether she has enough jelly beans to decorate all of the cookies in a batch she is preparing.

3-6

### Suggested Time

60 minutes

### Media Resources

Estimating Time from Rate QuickTime Video
How Many Jelly Beans? QuickTime Video

### Part I: Learning Activity

1. Tell students that they will watch a video in which Harry is trying to figure out whether or not he will be able to buy tickets for the show in time.

2. Tell the students that in the video, the booth closes at 6:00 PM, and it is 5:40 PM. when the video clip begins. Ask them to write down a general method to figure out how much time it will take to get to the booth to buy tickets.

3. Show the Estimating Time from Rate QuickTime Video .

4. Ask the students again to write down a general rule for estimating the amount of time it will take for someone standing in the line to get to the booth to buy tickets based on the rate at which the line moves. (Note, in the video clip, Harry uses the time to move 1 block multiplied by the number of blocks. Five minutes per block is a different form of rate than is often used such as miles per hour. It's the inverse of typical rates. Be careful.)

5. Distribute the Handout: "Estimating Time and Numbers" .

6. Ask the students to complete the handout.

7. Set out a rectangular- or square-based clear (glass or plastic) jar containing more than 100 objects (e.g., unifix cubes, M&M's, beads, jelly beans, etc.)

8. Ask students to figure out strategies for estimating the number of objects in the jar.

9. Tell students that they will watch a video in which Inez comes up with a method for estimating whether or not she has enough decorations for her batch of cookies.

10. Show the How Many Jelly Beans? QuickTime Video .

11. Compare and discuss the estimation strategies in the video clip and the strategies the class developed.

### Part II: Assessment

Assessment:Level A (proficiency): Students are asked to examine data from an experiment to test how long the flavor in gum lasts. They are asked to estimate the normal time for the flavor to be exhausted from a single piece of gum. From that estimate, they are asked to estimate how long it would take for an entire pack of 12 pieces of gum to run out of flavor, if 1 piece was chewed until it ran out of flavor, then the next piece was chewed, and so on.

Assessment: Level B (above proficiency): Students are shown a picture of a flock of birds with a grid overlay and asked to estimate the number of birds in the picture.

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