Duration
of Activity:
This
is a flexible activity and can be conducted in short increments
over one to two days. Allow 30 minutes for students to build
their sundials. Allow 15 minutes each time students go outside
to position sundials, and collect data.
Student
Prerequisites:
Students
should have:
 Prior
exposure to the topic of the Sun through reading and class
discussions.
 Experience
with measuring and tracing shadows. (See lesson
4)
 A
basic understanding of the Earth's rotation and how day
and night occur
Materials:

1 9inch white paper plate per student

one 4inch plastic straw per student

Regular and colored pencils

Rulers

Tape

Chalk
 Scissors
 Watch
or clock

Work sheet to record observations
Teacher
Preparation:
Allow
time to locate a quiet, sunny area to set up sundials and
to locate materials.
Work
Sheets:
"Sundial"
Work Sheets 


Need
help? 
View Completed Student Work Sheets 



Objectives:
Students
will:

Build
sundials and observe shadows as the Sun's position changes
over time.

Measure
shadows and note the position of the Sun.

Identify
patterns of change in the shadows.

Predict the length of shadows and where they will fall
on the sundial.

Share
data with peers and discuss how sundials serve as clocks.
Grade
Level:
Grades 13
Procedure:
Building
Sundials

Explain to students that they will build sundials and collect
data based on their observations.

Modeling the steps to building the sundial will make it
easier for young students to complete the task. Distribute
plates, straws, pencils, rulers, scissors and tape to students.
 Ask
students to find the center of the paper plate and mark
it with a dot.
 With
a pencil have students place 4 registration marks along
the edge of the paper plate (see
photos). Make one mark longer than the others. These
marks will help students reposition their sundials for taking
measurements throughout the activity.
 Ask
students to make 4 1/2inch cuts in one end of the straw
section. Flare out the cut portion of the straw tape
it onto the center of the paper plate. The straw should
perpendicular to the surface of the plate.
 Measure
and cut the straw to a 2inch length. (See
photos)
Using
the Sundial to Collect Data
Day
1:

In the morning distribute pencils, rulers, chalk and sundials
to students.
 Ask
students to place their sundials in a sunny spot on the
playground. Mark
the playground with chalk at the 4 registration points on
the edge of their sundials. Remember to make one of the
chalk marks longer so the sundials can be correctly repositioned.
(See photos)

Have students carefully trace the straw's shadow with a
pencil. Ask them to darken in the shadow with the
pencil and write the time at the tip of the shadow.

Ask students to note where the Sun is in the sky. Warn them
NOT to look directly at it.
 After
tracing ask students measure the shadow length and fill
in their data sheets.

Students will take more measurements later in the morning,
at midday, and in the early afternoon.

At the end of the day, ask students to predict where they
think shadows will fall in the late afternoon. Ask them
to look at their sundials and guess where the shadow would
be at 2 PM (or any other afternoon time). Using a red pencil,
have them outline the predicted shadow on their sundials.
Day
Two:
 Return
the sundials to their marked locations on the playground
the next afternoon, align registration points, and see if
the student guesses for the 2 PM shadow were correct.
 Students
may trace the real shadow to help compare it with their
guesses.
PostActivity
Discussion Questions:
Students
use their data work sheets during this discussion.

What did you observe? What did the shadows do?

When was the shadow the longest? Where was the Sun?

When was the shadow the shortest? Where was the Sun?
 Why
do you think the shadows change length?
How can you explain what you are observing?

How could you use a shadow to tell the time of day?

How accurate were your predictions? What could you do to
make them more accurate?
Assessment:
Use
the Sundial work sheet to assess your students' work.
Bibliography:
See
related books and websites.
