The circuits are built into large wood boards that mount easily onto an easel. The boards are labeled using conventional symbolism. Bulbs and batteries are easily removable--just be careful not to burn your fingers on the hot bulbs!
Evaporation of water on duck's head cools vapor inside causing low pressure, etc.
How it works:
Dippy Duck is a small heat engine consisting of a hollow glass barbell with opposite ends able to seesaw about a knife edge pivot. One end of the barbell is filled with a high vapor pressure liquid. The other end is empty on the inside and coated with absorbent flocking on the outside.
When the flocking is wet, evaporative cooling reduces the air pressure inside the empty end of the barbell, causing the liquid at the other end to get sucked up into it. As the liquid rises...