standard_description: Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
problem_activity: Narrative
The purpose of this warm-up is to elicit the idea that a centimeter is the length of the edge of a centimeter cube and to connect this with the length of a base-ten block composed of 10 centimeter cubes. This will be useful when students measure with base-ten blocks and report their measurements in centimeters in a later activity. While students may notice and wonder many things about these images, discussion of the attributes of the shapes are emphasized by the labels and the meaning of a centimeter are the important discussion points. Students use and revise their language to clearly describe the images (MP6).
Required Materials
Materials to Gather
Base-ten blocks
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Facing
What do you notice? What do you wonder?
A
[IMG]
B
[IMG]
Student Response
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Activity Synthesis
“How are the labels on both images the same? How are they different?” (They both show the length of one square. They both show 1 length unit. One says centimeter and one says cm.)
“Both labels show the length of 1 centimeter. Centimeter is a long word and can be hard to use to label your length units. We can use cm for short. ‘C’ represents centi and ‘m’ represents meter.”
Display a centimeter cube and 10-centimeter tool.
“If the length of 1 edge of a centimeter cube is 1 centimeter, how long is this block? Explain.” (It’s 10 centimeters long because it shows 10 blocks put together. Each block is 1 centimeter long.)
“When we practiced adding and subtracting by place, we used these tools to show ones and tens.”
“When we measure we will call them centimeter cubes and 10-centimeter tools to describe their lengths.”


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