Designing a Wind Vane

Purpose: This investigation helps develop design technology skills through the construction of a wind vane. Throughout the investigation, science process skills will be applied.

Materials

• 2 pieces of oak tag board or poster board
• 1 new pencil with a new eraser on it
• 4 pieces of transparent tape
• 1 plastic cup (yogurt cups)
• 1 straw
• 3 small pieces of clay
• 1 straight pin
• scissors
• compass or map

Procedure

1. Draw a triangle on a 5 cm by 5 cm piece of oak tag board or poster board to use as the "tail" of your wind vane. You can experiment with the size of this triangle to see if its size affects the performance of the wind vane.
2. Cut out the triangle and then trace it on another piece of your material. Cut out this second triangle and you should now have two identical triangles.
3. Place one triangle on the table and then lay the straw on top of it. The straw should start inside the triangle and extend through one of the points or "vertices" of the triangle. Use two pieces of tape to attach the straw to the triangle (fig. 1).
   
4. Place the second triangle on top of the first triangle and over the straw. Use tape to attach all three sides of the triangles together, covering one end of the straw (fig. 2).
   
5. Place the straw on your finger or another thin object and move it forward and backward until you find the point where the straw balances. This point will not be the center of the straw. Why not? Mark the balance point on the straw with a pen or pencil.
6. Get an adult to help with this part! Hold the straw so that the back edge of the triangle is pointing up and down. With an adult's help, insert a straight pin from the top side, down through the straw so that it pokes all the way through the other side and is pointing at the ground.
   
7. Now push the pin into the eraser at the end of your pencil. The straw should spin fairly smoothly around the pin. You may need to work it back and forth a little to loosen up the hole. The straw will probably slide down the pin and rest on top of the eraser.
8. Use the pencil to attach your wind vane. You can push it into the ground, tape it to the top of a fence post, or stick it through the bottom of an upside down cup or container that is well supported.
9. Using a compass or a map of the area, determine which direction is North, then mark the directions North, South, East, and West around the center of your wind vane.
10. Now you can use your wind vane to determine the direction from which the wind is blowing. It will always point toward the direction that the wind is coming from.
11. Some things to think about:
    • Record how the wind direction changes throughout the day or week. Do you see any patterns?
    • How does your data compare to the weather reports on the evening news? If you get different wind directions, what are some reasons for the differences?
    • Can you think of ways to improve your wind vane design?
    • Can you think of any people or professions that need to rely on wind direction information everyday?
    • Does the wind vane tell you the speed of the wind? If not, do you have any ideas on how you could determine the wind speed?
    • How does the weather today depend on the wind direction? How about tomorrow's weather?