Ever feel like you've wasted your breath on something? Well now every breath you take is going to spread total wonder and joy with this straw propellor. Also a bit of saliva!

With three straws only you can create this double-spinner of a physics lesson in forces and air pressure. It takes a bit to get started, but once you get the dynamic, you can modify to make some pretty wonderful designs.

The details:

What: A Straw Propellor!
Time: ~ 10 minutes first time, 3 minutes after
Cost: ~ 5 cents
Materials:
- 2 large straws
- 1 skinny straw
- Tape
Tools:
- Scissors
Concepts: Air Pressure, Forces, Newton's Laws

(Thank you to our propellor model Charlie!)

Step 1: Cut Two Diamond Holes in the Skinny Straw

Start by cutting these two holes spaced apart on the skinny straw. Fold it back, and cut out a triangular wedge so that when it unfolds, it makes two diamonds.

Keep some distance between the two to, because this is where the large straws will go and you don't want them getting tangled with each other.

Step 2: Tape the End of the Skinny Straw

Tape off one end of the skinny straw so that when you blow in to it, air can only escape out the two holes. Trim off excess tape.

Step 3: Make a Through-hole in a Large Straw

Take your first large straw and cut a through-hole by bending it in half, and making a diagonal cut on both sides of the fold. See the diagram for details and play around with it. It should come out looking like the photo.

Step 4: Tape Both Ends of the Large Straw

Tape both ends of the straw closed so that the straw is squeezed flat. When you look through the through-hole, the flat ends of the straw should be perpindicular to the ground. This is important for getting them to spin.

So again, hold the straw up to eye level so you can see through the through-hole. The ends of the straw should be pinched together and taped such that the flat edge is pointing up and down.

Step 5: Cut Notches in Ends of Big Straw

Now it's time to cut notches in the end of the big straw. Cut a triangular wedge on the top-side of the left end of the straw and the bottom-side of the right end of the straw.

This is so that when air gets pushed out the ends of the straw, with the forces going in opposite directions, it will cause the straw to spin.

Check out the first diagram for details on this.

Step 6: Thread Skinny Straw Through Large Straw

Thread your skinny straw in to the through-hole. I like making a tape stopper around the skinny straw to keep the the large straw in place while it spins.