41. Measuring the Wind

Subject: Science
Group size: Small or large
Time: 45 minutes
Type of activity: Student investigation
Teaching strategy: Guided discovery
Concepts: Wind speed
Skills: Measurement, Data collection, Inference

Objectives: to use an anemometer to record the wind speed in non-standard measurement: to relate wind speed to flying conditions.

Materials: Plastic funnel. Sharpened pencil a bit taller than the funnel. 2 cardboard strips with a hole punched in the center of each. Masking tape. Scissors. 4 open boxes made from graph paper. Marker. Stopwatch or clock with second hand.

Procedure: (Teacher) Make an anemometer using the directions on the following page or have the students make them.

Have students create a breeze by blowing into the boxes. Count the number of times the colored box passes the marked point. (Do it per 15-second time periods and then convert to kilometers. A count of 30 in 15-seconds (2 counts per second) would be approximately the same as a wind speed of 6 to 7 kilometers per hour.) Have students blow softly and count and then blow more strongly and measure. What happens? Use a fan or a hair dryer and measure. Test it outside in various winds. Talk about the differences and fly paper airplanes to test when the wind speed causes problems.

Headwinds. Have students throw their paper airplanes into the wind (outside or toward a screened fan). Have them throw their airplanes without any wind. Discuss the differences in speed of the planes. Ask if there is a 20 mile an hour headwind and a plane is flying directly into it at 100 miles an hour, how fast is the plane actually flying over the ground?

Crosswinds. Experiment with throwing the paper airplanes to a specific target with a crosswind as a problem. What do they have to do to get the plane to go where they want it to go? Investigate different wind speeds.

Anemometer: What to do… [ annotated assembly diagram p108]

1. Put the pencil point through the hole in the funnel.
2. Place the center hole of each cardboard strip on the pencil point. Put the strips at right angles and tape them together.
3. Color one of the open boxes.
4. Tape the boxes to the ends of the strips. Make sure the box openings are facing the same direction – either clockwise or counterclockwise.

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