Mystery containers
Scientists often work out what is inside something without opening it. Imagine three closed boxes, A, B and C. A grown-up has put one thing in each: a stone, a little water, and nothing but air. You may only shake each box and listen. A box with a stone makes a clunk and a bump. A box with water makes a slosh. A box with just air is quiet, and it does not feel heavy. Each sound is evidence. You do not open the boxes, and you never taste or smell anything. Scientists explain what they cannot see with a model. We will learn that all matter, solid, liquid or gas, is made of tiny moving particles. The difference between the states is how the particles are arranged and how freely they move.
| Box | Sound when shaken |
|---|---|
| A | clunk and bump |
| B | slosh |
| C | quiet |
| Box | What she hears | Her prediction |
|---|---|---|
| A | slosh | water |
| B | clunk | a stone |
| C | nothing | only air |
Mystery boxes (a grown-up prepares them). A grown-up seals three small boxes: one with a stone, one with a little water in a closed jar, and one with only air. Shake, listen, and write a table: box, sound, your prediction. Do not open them until you have written your predictions. Then the grown-up opens them.