The Wind Gyro.  This elegant top can be spun by hand, but why use your fingers when you can rely on science? Simply blow a steady stream of air downward onto the top, and it will start to silently spin! Use a straw for more concentrated airflow, and it will keep going for as long as you continue to blow upon it. Similar to a wind or water turbine, this top is a fascinating way to teach about aerodynamic design, energy, friction, rotational inertia, and gyroscopic stability. Use it "freestyle" on your desk or set it upon its magnetic storage case and watch it go. You can even suspend the top upside down and power it using your breath! Whichever way you try, this top is an amazing demo. Approx 4 cm tall.