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
 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







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

Length
of Shadow





 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.
 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?
