Limiting Reactant

Description:  In this phenomenon both magnesium metal and hydrochloric acid are limiting reactants.  I have used this in a chemistry class, framing it as "The Case of the Mixed Up Masses".  I tell them that I added varying amounts of magnesium metal but I forgot to label the flasks.  If done correctly they should get the curve seen below.  I learned about this on the NSTA Resource page.  

Web Resource:  NSTA Stoichiometry Balloon Race

Professor Jim Holler of the University of Kentucky demonstrates the concept of limiting reactants with magnesium and hydrochloric acid.

The Drinking Bird

Description:  The drinking bird is a toy heat engine.  The source of energy in this phenomenon is a mystery to most students.  It is said that Albert Einstein and his wife Elsa were fascinated with this toy when they visited Shanghai in the 1920's. 

Web Resources:  The Engineering of the Drinking Bird, The Drinking Bird - Wikipedia
 

Very innovative creation, the bird will "drink" the water and keep moving. If you keep refilling the water, it will run forever! Experimented with one cup of water, it runs for 3 days non-stop until the water drop below the level it can dip on.