Return to Mathematics IndexEstimation Contest

Sandra A. King-Bryson Saucedo Magnet School

2850 W. 24th. Blvd.

Chicago, Il. 60623

(312) 534-1770Objective:

Students will gain a more concrete understanding of the subtle difference

between a guess and an estimate.Materials Needed:

Large box of Cheerios or other similar cereal

32 oz. or 48 oz. container (translucent or transparent)

Cups for each student or group of students (an odd size cup will offer the

greatest challenge, i.e. 6.8 oz. or 7 oz.)

Paper plates

Paper and pencilStrategy:

Estimation is a powerful mathematical idea to be used both in solving problems

and in checking the reasonableness of results. When the student wants to know

about how long it will take to earn enough babysitting money to buy a new

bicycle he or she can estimate the answer. Estimation should be used to solve

problems for which exact answers are inappropriate and to check computation

results.

We all make estimates everyday. How long will it take you to walk to school,

how much food should I put on my plate for dinner, how many times will Mother

call me before she comes to look for me, etc.?

The Estimation Contest is a fun and easy way to allow the students to make

"educated guesses".

1) Fill the large container (32 or 48 oz.) with the Cheerios or similar cereal.

Try to use only whole pieces, not broken ones. Count the number of pieces.

2) Write the number of pieces and put this information in a safe place. (Do

not put this information on the container).

3) Give each child, or group, a paper plate, a cup, paper and pencil. Tell the

students the capacity of the cup (7 oz., 8 oz., etc.). Tell the capacity of

the large container.

4) Give each child more than enough cereal bits to fill their cup.

5) Ask students to estimate the number of cereal bits in the large container.

They may use whatever measuring devices they think will help them get the

best estimate.

Example: You have a 48 oz. container filled with Cheerios and the students are

given a 6 oz. cup:

VOLUME OF CONTAINER_{= number of 6oz. cups required to fill the}VOLUME OF CUP_{ large container}Therefore:48 oz._{ = # of 6oz. cups required to fill large container}6 oz. The number would be 8 8 cups X 223 cereal bits in a cup = 1,784 cereal bits in the 48 oz. containerQuestions:

1. How could you make your estimate more accurate?

2. Given a weighing apparatus, could you estimate the weight of the cereal bits

in the large container?Extension:

Show children the difference between a guess and an estimate. Set up several

guessing stations in your classroom. One might be guessing the length of a

piece of rope, another might be guessing the amount of popcorn kernels in a

container, another might be guessing the amount of liquid in a container, etc.

Point out to the students that when they guess they really aren't basing the

guess on any factual information. Explain that an estimate is based on some

amount of knowledge or facts that can be obtained.Acknowledgements:

M. Matyas and J. Combs, "Proyecto Futuro". American Association for the

Advancement of Science (AAAS).