The purpose of this activity is for students to create and label the tick marks on a yardstick using what they know about length units, comparing length, and adding and subtracting length. They use the sides of a 3-by-5 inch index card to mark off all inch marks from 1 to 36. They look for ways to use the structure of a measuring tool, the known lengths of the index card, and what they know about adding and subtracting lengths to mark and label new tick marks. When students identify information they need to know to answer a question and make assumptions about information not given in a situation, they model with mathematics (MP4).

• Invite previously identified students to share.
• Consider asking:
  • “Which numbers did you mark first?”
  • “Which numbers were easy to find?”
  • “Which numbers were harder to find?”
  • “Did you run into any problems? How did you solve them?”

The purpose of this activity is for students to compare the yardsticks they made in the previous activity. Students discuss how the yardsticks are the same and different, why they might have ended up looking different, and what would happen if people measured with tools that were not exactly the same. When students think about the real-world implications of their model, they model with mathematics (MP4).

• Invite previously identified students to share.
• “Now that we have talked about some differences in our yardsticks and you have heard some different strategies for marking each inch, take some time to make any necessary changes to your yardstick to make it more accurate.”