To make a homemade wind vane, you need a plastic soda bottle filled with sand or tiny pebbles as a base, two pieces of cardboard, a piece of straw, a pencil and a straight pin. Cut the first piece of cardboard into a square about 2 to 3 inches, and cut the other one into a triangle a little smaller than the square one. Staple or tape the cardboard pieces on each end of the straw, with one of the triangle points pointing away from the straw -- making it look like an arrow. Locate the middle of the straw and push the straight pin through the straw. Push the end of the pin into the pencil's eraser and so the arrow moves freely. Secure the pencil by pushing it inside the soda bottle with pebbles. Once the wind vane is built, go outside, find north using a compass, and position the wind vane in the same direction. See which direction the straw blows to determine the current movement of the wind.
Kites are normally flown for recreation and amusement, but they also present a lesson about understanding the power of wind. Form a group wherein each of you, or a group of kids, creates kites of varying shapes and designs. Launch the kites and start observing how each kite catches the wind and stays in the air. Learn about aerodynamics and how to manipulate objects by comparing different sizes of kites and their response to wind. Once done, create other kites with more aerodynamic designs based on your observations.
Kids -- and adults for that matter -- may find windmills difficult to build, so a simple pinwheel or whirligig will do. These are also perfect for classrooms due to their low cost. As a pinwheel starts spinning, it reflects upon the same general idea of a large-scale windmill. The turning of the propeller is harnessed by connecting it to a turbine and electrical generator, which ultimately serves to create electricity.
If you're interested in aircraft technology, you can build a homemade wind tunnel. Wind tunnels serve as a testing ground to see the effects of wind on a solid object; it's commonly used to see if an aircraft's design is aerodynamic. For classroom purposes, settle for a make-shift version using a box and a leaf blower, or a cardboard tube and a small fan. With this activity, concepts of lift and drag can easily be seen (items, such as paper to replace an actual airplane, make great substitutes).