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Sandra A. King-Bryson Saucedo Magnet School
2850 W. 24th. Blvd.
Chicago, Il. 60623
Students will gain a more concrete understanding of the subtle difference
between a guess and an estimate.
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 and pencil
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
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
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
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
The number would be 8
8 cups X 223 cereal bits in a cup = 1,784 cereal bits in the 48 oz.
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?
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.
M. Matyas and J. Combs, "Proyecto Futuro". American Association for the
Advancement of Science (AAAS).