A balance is set up with two pieces of iron wool. One piece is set alight: it appears to be getting smaller but, mysteriously, the balance tips the other way.

Curriculum links include chemical...

Two translucent liquids are mixed. At first, nothing happens: the resulting solution is still translucent. Suddenly, with no warning, the solution turns blue-black all at once.

Curriculum links include redox reactions, rate of reaction, kinetics