Lesson 5

Arm Span vs. Height

Est. Class Sessions: 4–5

Daily Practice and Problems

Teacher Notes
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TIMS Bit

This TIMS bit is a good item to discuss orally. Show students a ruler with centimeters and inches. Point out that the ruler is 12 inches long and about 30 centimeters. They can use the ruler as a point of reference.

  1. Crazy: The number of cm on a 12-inch ruler is 30 cm.
  2. Could be: Fourth-graders are between 50 and 60 inches tall. A yardstick is 36 inches. A meterstick is about 39 inches.
  3. Could be: I once measured the width of my wrist and it's about 4 cm.
  4. Crazy: 20 inches is longer than a 12-inch ruler.
  5. Could be: If I line up 3 metersticks on the floor, that is about the length of my small car.

S. Measurement: Could Be or Crazy?

Without measuring, decide whether each measurement is a “could be” measurement or a “crazy” measurement. Explain how you decided.

  1. The distance from a doorknob to the floor is 30 cm.
  2. The distance from a doorknob to the floor is 40 inches.
  3. The face of a watch is 3 cm wide.
  4. A fourth grader's foot is 20 inches long.
  5. A car is 3 meters long.