Use written exercises and practical activities to stimulate thinking and concept development and application of scientific ideas - at the start or end of a class or for a revision exercise.

Ask the students to explain/describe/answer in their own words in writing or orally to a partner using scientific ideas they have already covered or suggest explanations for 'unknown' situations or problems. These problems can be presented in writing based on everyday observations or given as experiments which they have to explain. Students should be encouraged to think up other experiment to test their solutions. PLEASE TRY SOME OF THESE OUT AND LET ME KNOW THE EEFECT.

Some examples:
1. When a glass of cold water is left standing in a warm room bubbles appear on the glass.

2. When a steel screw is left out in the rain it goes rusty but a brass screw doesn't.

3. A can of diet Coke floats in water but regular Coke sinks.
(Does this apply to other brands of soft drink as well e.g. Diet 7Up versus normal 7Up.)

4. When there is a very cold spell the cold water may stop flowing and when it thaws the house is flooded.

5. A newspaper stays white if left in a newspaper rack or in a pile, but if left on a window ledge it changes colour.

6. When lit cigars burn slower than cigarettes and may even go out.

7. When a thermometer bulb is coated with ethanol the temperature goers down faster than when butanol (or water is used).

8. When food is first put in a new fridge, ice forms on the inside of the fridge.

9. Food left out on a window ledge dries out but also if left open in a fridge.

10. Some timber doors are easier to open in the summer than in the winter.

11. When clothes pegs are left out on the line over a period of time they fall apart.

12. On a sunny day pond weed produces bubbles of gas but not on a dull day or in the shade.

13. When milk is left standing in a warm room it separates out into two layers.

14. You can tell the difference between fresh and stale eggs by placing them in water. A fresh egg sinks and a stale egg floats. In salted water both types of egg float.

15. A boy observes that when a girl comes into the room it is some time before he knows if she's wearing perfume or not.

16. When a can or bottle of carbonated drink is poured into a glass, bubbles often appear to come from one place on the glass.

17. Why when one takes a deep breath is the urge to breathe out not in?

18. Take an empty drinks can, with rung pull attached, and bore two holes on opposite sides with an awl or nail. In one case (A) bend the awl away from you on removing it and in the opposite hole (B) bend the awl towards you. Suspend the can from a string attached to the ring pull, fill with water with thumb and forefinger over the holes, and then remove to allow water to escape. Predict the direction of rotation and explain what is happening.

19. Blow up a balloon and then release it. Explain the direction it travels and what is happening.

20. Take two sealed plastic bottles of water, one carbonated and the other still. Make a small hole with an awl or nail near the bottom of each. Predict and explain what will happen. What happens is the cap is removed?

Several of these items were contributed by teachers attending the Lucent Summer School at the University of Limerick, 25-29th. June, 2001

Please send in your ideas for experiments or situations which test understanding of scientific principles.