Anemometer

What you need:

• 5 small paper cups

• 2 straws

• Hole punch

• Sharpened pencil with eraser

• Thumbtack

What you do:

1. In one paper cup, punch four holes at equal distance from each other.

2. Thread both straws through two holes on opposite sides of the cup.

3. On the other four cups, hole-punch two holes on opposite sides of each cup from one another.

4. Take the four cups and slide them onto the straws so that they're facing the same direction.

5. Color the bottom of one cup so that you see it when it spins.

6. Using the sharpened side of the pencil, punch a hole in the bottom of the center cup. Then, slide the pencil into the hole you just punched, with the eraser pointing up so that it touches the center of the straws.

7. Press the thumbtack through the straws and into the pencil eraser firmly.

8. Take the anemometer outside and stick the pencil into the ground, and watch the anemometer spin.

Questions to ask:

1. Why do you think it is important to color one of the cups?

2. How many rotations do you count within 30 seconds?

What's the science:

Meteorologists use a variety of tools, such as anemometers, to learn about weather patterns and make predictions. Anemometers measure wind speed and are very important. Wind speed is calculated by counting how many times the anemometer rotates in a given period of time. 

As air does not blow at a consistent pace, the readings are often averaged together to determine the speed. When meteorologists notice changes in wind speed, that means the weather is changing, which is important for them to report so that we don’t get caught out in a storm.