Experiences

The right language chemistry

M.C.

Romania

High Secondary School

Chemistry

Teaching in class, Laboratory

Direct

If a teacher uses the right language chemistry is like a magic land whose tricks are gradually revealed. Children are fascinated with tricks, their explanations and what is behind them. Especially for the little ones any experiment can be like an adventure to a magic land, whose keys they own. For instance they know that oil and water do not mix. They know that you can mix them together and shake as hard as you like but they'll never mix; you can create a bit of suspense by telling them that mixing them can be possible if you use the right trick. Ask students to mix water and cooking oil in a pot and shake it. Ask them to put the pot down and notice if anything has happened. They will notice that the oil will float above the water on the top. While water often mixes with other liquids to form solutions, oil and water does not. Water molecules are strongly attracted to each other, this is the same for oil because they are more attracted to their own molecules they just don't mix together. They separate and the oil floats above the water because it has a lower density.
Ask students to try adding some dish washing liquid or detergent. Detergent is attracted to both water and oil helping them all join together and form something called an emulsion. This is how we wash our dishes.