Wind Speed Measuring With a Homemade Anemometer

Four small paper or plastic cups

Two thin wooden dowels or sturdy drinking straws

A pencil with a flat eraser top

A pushpin

A small square of cardboard

Tape

A timer

A marker for coloring one cup

Build the base: poke the pencil point-down through the center of a small cardboard square. The eraser end should stick up and serve as the pivot point.

Create the cross: tape or staple two dowels (or straws) into a plus sign. Pin the center of the cross to the pencil eraser using a pushpin. The cross should spin freely.

Attach one paper cup to each end of the cross, all facing the same rotational direction (so the open end of each cup catches the wind on one side of the rotation). Tape securely.

Color one cup with a marker — this is your counting marker so you can track rotations.

Take your anemometer outside to an open area. Set a timer for 30 seconds and count how many times the colored cup passes a fixed point. That number represents wind speed.

Record the count at different times: morning, noon, afternoon. Try different days. "Is it windier today than yesterday? Is morning or afternoon windier?" You're building a data set.

The pushpin must allow the cross to spin very freely. If it's tight or wobbly, the cups won't catch light breezes. Test indoors by blowing on it.

More rotations in 30 seconds = stronger wind. You can create your own scale: 0-5 rotations = calm, 5-10 = light breeze, 10-20 = moderate, 20+ = windy.

Pair this with the backyard weather station for a complete meteorology setup.

Real anemometers at weather stations work on the same principle — your child just built a simplified version of professional equipment.

Track data for a week. Graph the results. Your child is doing real data science with a paper cup and a pencil.