This does not require any calibration like a few of the other experiments in this series, but you won't be able to read the exact wind speed. Still, this is a fun way to teach students about how meteorologists measure wind speed.
Here's what you need: four cupcake liners, a scissors, four thumb tacks, a spool, a pencil with a good eraser still attached, and a needle or pin that's a bit longer than the width of the cardboard, and two strips of thick cardboard of equal size, approximately the width of a cupcake liner and five times the length. While the exact length doesn't particularly matter, they must be the same size.
Step 1: Cut a notch in the center of each cardboard strip, exactly half of the width and to the thickness of the other piece of cardboard. This will allow you to fit the two strips of cardboard together to form what looks like a plus sign.
Step 2: Glue each of the four cupcake liners to the end of each cardboard strip. They should be aligned so that they all face the same way along the edge of the circle. What that means is that if looking at the end of the cardboard strip from the side, you always glue the cupcake liner to the same side as you spin the plus sign-shaped cardboard around. This way, no matter what the wind direction, the air will catch at least one of the cups to get it to spin. When looking at the top, each cross section of the cardboard will have a cupcake liner on each side. See figures if you're still confused as it isn't the easiest to explain.
Step 3: Place tip of pencil into center of spool so it is free to spin.
Step 4: Once glue is dry, it's time to place the cardboard plus sign with cups glued on to the top of the pencil. Very carefully, place the needle through the exact center of the cardboard where the two sides cross. Then, stick the part of the needle or pin that sticks out the bottom into the center of the eraser of the pencil.
That's it! The faster the wind blows, the faster the cups will spin. That's just like a real anemometer, just without the sensor that detects how fast it spins and translates that into a wind speed.
More build at home weather instruments can be found HERE.