Lesson 5

Arm Span vs. Height

Est. Class Sessions: 4–5

Developing the Lesson

Part 2. Launching the Lab

The completion of the vignette sets the stage for the laboratory investigation. In the vignette, Irma and Jerome looked for patterns in hand length and height to make predictions. In Arm Span vs. Height, each group will measure, record, and look for patterns in arm span and height to make predictions.

Before they collect the data, ask:

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  • Do you think we can predict the height of a fourth-grader if we know his or her arm span? Why or why not? (Students may recall that there was a relationship between hand length and height in the story The Four Servants that enabled them to predict the giant's height.)

Model the measurement procedure.

Ask questions such as:

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  • What should we do to measure accurately?
  • What variables should we keep fixed?

Fixed variables are variables in an experiment that are held constant or not changed.

The class as a group will need to decide upon some rules that will make the measurement consistent across the class. These measurement rules will be one type of fixed variable.

For example, the class might decide that everyone should:

  1. Remove their shoes.
  2. Stand straight and place their feet together when they are being measured.
  3. Place a ruler flat on the top of the head of the classmate being measured, touch the ruler to the meterstick, and measure to the nearest inch.
  4. Start at the edge of the first meterstick when arm span is being measured. (The tip of the longest finger should line up with the edge of the first meterstick.) Students have a tendency to lean up against the metersticks and spread their arms out without touching the edge or 0. Refer to Figure 1.
Student Guide: 37 38
Answers
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SG_Mini
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SG_Mini
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Student Activity Book:
Master:
Setting up measurement station with metersticks
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