As a precurser to the multiplication and division units in 3rd grade, students convert between inches, feet and yards during the measurement unit in the fall. Students are not expected to use multiplication to convert; they explore different strategies that will build their multiplication readiness.
In this activity, students represent inches, feet and yards with integer bars using the following website:
http://arcytech.org/java/integers/integers.html
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Students use bars to represent the number of inches found in a foot. Students often struggle to remember this basic conversion, so they create a representation that focuses on the number 12 |
Students then create a model that shows the number of inches in 3 feet. They keep a function table of the number of inches in a certain number of feet.
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Students can see the conversions in the models they have made. They can count the number of inches in the model or they can use repeated addition (adding 12 inches for each foot). Students should be able to verbalize that to find the number of inches in 6 feet, they would simply have to add 12 to 60. Most students in third grade understand the logic of the function table, and multiplication is not necessary. To find the inches in four feet, they simply have to add:
12+12+12+12 |
In the process of finding the number of inches in three feet, they have also found the number of inches in 1 yard. In third grade, students are only expected to convert between two units (such as inches to feet or feet to yards). However, using the models and the function tables, students can easily see how to find the number of inches in 2 yards.
This model shows the number of feet in 3 yards. By completing this activity, they can strategize how they can find the number of inches in 1 yard, in 2 yards and in 3 yards.
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Students can continue the conversions. It is important they understand the logic of adding on 12 inches for every foot. |
As students learn the logic of converting between units, they should also be exposed to word problems which necessitate that they apply the conversions in a meaningful way. |
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Finally, students use the Graph Master program to represent converting between inches and feet in a different manner. Students simply input the values they have found from their function tables. The graph focuses them on the fact that inches count by 12. |
Converting between inches, feet and yards not only prepares students for multplication and division later in the year, it also readies them for algebraic reasoning in later years. Explore the links above to lessons in later grades.
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Indicators:
3.3.3.2 convert between inches, feet,and yards.
3.3.4.1 use length, capacity, weight, temperature, and time to solve problems.
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