8th Grade Math Home > Teacher Resources > Activities > The Shadow Knows: Teacher Notes

The Shadow Knows: Teacher Notes

MA.7.A.1.1
MA.7.A.1.6

Conceptual Knowledge

Ratios
Proportions
Measurement

Procedural Knowledge

Measuring Lengths
Solving Proportions

Problem Solving
Reasoning
Communication
Connections
Representation

Can you determine the height of a telephone pole or tree without climbing to the top?

Students work in groups of 3 or 4


  • 1 short metric measuring tape
  • Sunshine

  1. Choose two students from your group. Measure their heights and the lengths of their shadows. Record your data in the table below.

    Student Name
    Height
    Length of Shadow
         
         

  2. Measure the length of the 3rd and 4th students’ shadows. Record their data in the table below.

    Student Name
    Length of Shadow
       
       

  3. 3. Use the measurements in a ratio to predict the height of the 3rd and 4th students.

    Formula:
    Height of Student 1
    =
    (x)
    Height of Student 3
    Length of Student 1’s Shadow
    Length of Student 3’s Shadow

    Cross multiply and divide to find student 3’s height.
    Repeat for student 4.

  4. Pick a nearby object (tree, telephone pole) and measure its shadow length. Use the previous ratio to find the height of the new object.

As a result of this activity, students will be able to determine heights of objects that cannot be directly measured.

Compare results from different group findings.
What applications would this activity have in the business world? What occupations would need this skill to do their job?

8th Grade Math Home > Teacher Resources > Activities > The Shadow Knows: Teacher Notes