"The answer, my friend, is blowin' in the wind." At least that's what Bob Dylan said.

Air currents, air circulation, and wind (fast air currents) are important to all kinds of life. Air that just hangs around without moving can get "stale." In another project, we can discuss the ways that air currents are valuable. Or, we could find a book that would tell us.

Meanwhile, we can make some instruments that can measure or show the direction of air movement. What are some of the ways we can tell that the air outside is moving, and not just
hanging out getting stale? We can see leaves moving on trees, or, if the wind is blowing hard, entire trees sway. Dust on the ground will sometimes move in little whirlpools, while leaves that have fallen are traveling along the ground. Litter-bugs have dropped papers, and they scoot around as though they were inhabited by ambulatory critters! In a stiff wind, people with long hair look like sea serpents. Look at the flagpole, and see our flag rippling in the wind!

Do we know about propellers on airplanes? They push on the air and make the planes go. (Boat propellers push the water.) Do we know about pinwheels? Pinwheels are fun. Let's make some.

On a white card, make three concentric circles with diameters of 2 1/2 inches, 2 1/4 inches, and 1/2 inch. Set the ends of a compass (the kind used to make circles) 1 1/4 inches apart.

Place the point of the compass anywhere on the outer circle, and make six consecutive marks around the outer circle. Using a ruler, connect opposite marks with a straight line. Draw a line along the ruler from the edge of the middle circle to edge of the inner circle at every mark, alternating so that one line is heavy and the next is dotted. Now connect every other point on the 1 1/4 inch circle with a heavy line.

Carefully cut out wind foils along the dark lines, and fold along the dotted lines as illustrated.

The detector can be mounted on the eraser end of a pencil with a pin. Be sure it spins freely.

The device can be used to detect wind currents in different parts of the school grounds or classroom. As you know, we can even run with them, or just swish them through the air to
make them spin.

Here's another indicator we can make. Stick a pin through the middle of a plastic straw, and attach it to a cork. Turn the straw on the pin a few times so that it turns freely.

Next, pinch one end of the straw together and fasten a paper clip to the pinched end. Glue or tape a lightweight index card in a horizontal position on the other end. Level and balance the straw by moving the paper clip.

Use a protractor to make a scale like the one illustrated. Attach the scale to a large side of a small cereal box. Glue the cork to the center of the scale.

When the box is held in a vertical position, you will see that the detector arm moves up and down and indicates the relative force of the rising or falling air.

When held in a horizontal position, it measures air that is moving horizontally.

Hold the detector in various locations (e.g., over lighted bulbs, beneath open refrigerator doors, over radiators or registers, below windows).

Why would we hold our indicator near a source of heat or a source of cold? Does heat or cold affect air movement? In what ways?

Measurements taken at different times and places can be recorded and compared.