Solar-Powered Sundial: DIY Shadow Clock

 

Ages: 8-12

Objective: Engage children in an intriguing and educational activity to construct their own shadow clock, also known as a sundial, while learning about the Earth's rotation and the concept of timekeeping.

Materials Needed:

1. Large paper plate or cardboard
2. Pencil or pen
3. Ruler or straight edge
4. Compass (for drawing circles)
5. Scissors
6. Small stick or dowel
7. Modeling clay or playdough
8. Sunny outdoor location

Procedure:

1. Begin by drawing a circle on the paper plate or cardboard using a pencil and compass. This circle will serve as the base of the sundial.

2. Use a ruler or straight edge to divide the circle into 12 equal segments, representing the hours of the day. Label each segment with the corresponding hour, starting from 6:00 AM and ending with 6:00 PM.

3. Cut out a small notch or triangle from the edge of the circle to serve as the gnomon, which will cast a shadow onto the dial to indicate the time.

4. Attach a small stick or dowel vertically to the center of the circle using modeling clay or playdough. Ensure that the stick is positioned perpendicular to the dial and aligns with the North-South axis.

5. Take the completed shadow clock to a sunny outdoor location and place it on a flat surface, ensuring that the gnomon is pointing northward and the dial is level.

6. Observe as the shadow cast by the gnomon moves across the dial throughout the day, marking the passage of time as the Earth rotates on its axis.

7. Encourage children to periodically check the shadow clock and record the time indicated by the position of the shadow relative to the hour markers.

Explanation:

• The shadow clock, or sundial, operates based on the principle that the position of the Sun in the sky changes throughout the day due to the Earth's rotation on its axis.
• As the Sun moves across the sky from east to west, the shadow cast by the gnomon moves in a corresponding manner, allowing observers to determine the time based on the position of the shadow relative to the hour markers on the dial.
• By aligning the gnomon with the North-South axis, the sundial can accurately indicate local solar time, with noon corresponding to the moment when the Sun reaches its highest point in the sky.

Extensions:

1. Explore the concept of solar time versus standard time and discuss the factors that affect the accuracy of a sundial, such as the Earth's axial tilt and the observer's geographical location.
2. Encourage children to experiment with different designs and materials for their shadow clocks to see how they affect the accuracy and functionality of the device.
3. Discuss the historical significance of sundials as one of the oldest timekeeping devices used by civilizations around the world.
4. Challenge kids to create their own personalized shadow clocks with unique designs and decorative elements, incorporating artistic expression into the project.
5. Host a sundial observation session where children can compare the time indicated by their shadow clocks with the time shown on standard clocks or devices.

Safety Note:

• When using scissors and sharp objects, remind children to handle them with care to avoid accidents. Supervise younger children closely during the construction of the shadow clock.