Why is it important to estimate?
National Council of Teachers of Mathematics Standards:
Numbers and Operations
- Understanding meanings of operations and how they relate to one another
- Compute fluently and make reasonable estimates
Measurement
- Understand measurable attributes of objects
- Apply appropriate techniques, tools, and formulas to determine measurements
This activity helps students practice estimating the mass of several objects.
(BACKGROUND INFORMATION)
This is what we already know about estimation:
- Estimating helps you plan ahead and check your work to see if your answers make
sense.
- The ability to estimate also helps determine if answers to math problems are
reasonable. Sometimes we round numbers to be able to add or subtract them more
easily.
- The more practice or experience we have with numbers and amounts helps us
estimate more accurately.
Activity - Estimate the Mass
Per group:
balances, gram stackers or other known amounts of mass, various
objects with different mass, paper to create a chart
Pre-Lesson Instructions:
- Students should work in groups of four to six.
- Each group will need a balance, a set of standard mass amounts,
and a set of objects to be measured. For example, a set of objects could include
a tennis ball, a pencil, a dictionary, a pack of flashcards, etc.
- Discuss the term "mass" with your students. Mass is the amount
of material found in an object. Mass is measured in grams using a
balance. If this is the first time that students have measured mass,
practice this skill with them before starting this activity.
- Explain that students will be asked to estimate the mass
of the items BEFORE they actually measure the mass of the items.
- Practice estimating with the group by holding up an object that is NOT in the
set of objects to be measured. Pass the object around and ask students to "guess"
the mass of the object. As a comparison, tell them that a paperclip is about one
gram. Record "guesses" so that they can be seen.
- Measure the object. Discuss the differences between the student "guesses" and
the actual mass. Record the actual mass of the object on the board and suggest
that students remember this amount to help them with the activity. Let students
hold the object whenever they may need it as a point of reference.
- Display the chart and ask students to copy the chart on their own paper.
- Ask students to begin the activity by holding one item and estimating its
mass. Ask students to record their estimates in the correct column.
- As soon as the estimate is recorded, instruct students to measure the mass of
the object. Show students how to calculate the "oops" column by finding the
difference between the estimate and actual measurement.
- Instruct students to estimate and measure each item, one at a time.
- Discuss how "estimating" is a skill that improves with practice. Students
should find that their estimates are more accurate with more practice.
Name:________________________________
Estimator Chart
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| Object |
Estimate |
Mass |
Oops! |
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Total Oops!:_____________________
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Extension:
Discuss other situations when estimating is a helpful skill.
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