Demonstrations without explanations are of little value -- they are perceived as being merely magic tricks. Questions during and after a demonstration can be most effective in leading pupils to an understanding of the principle or phenomenon displayed.
To be effective and to promote pupil understanding and retention demonstrations must be:-
Inspire another generation
1. Know the properties of all the chemicals and the chemical reactions involved in all the demonstrations you present. Refer to "Safety in School Science"and "Safety in the School Laboratory - Disposal of Chemicals" published by the Dept. of Education & Science.
2. Comply with all the National Safety and Health regulations.
3. Wear appropriate eye protection for all chemical demonstrations.
4. Warn members of the audience or class to cover their ears whenever a loud noise is anticipated.
5. Plan your demonstration so that harmful quantities of noxious gases do not enter the local air supply.
6. Provide safety shield protection wherever there is the slightest possibility of a container, its fragments, or its contents being propelled with sufficient force to cause personal injury.
7. Arrange to have a suitable fire-extinguisher at hand whenever the slightest possibility of fire exists.
8. Do not taste or allow spectators to taste any non-food substances.
9. Do not use demonstrations in which parts of the human body are placed in danger.
10. Arrange for appropriate waste containers for and subsequent proper treatment for materials harmful to the environment.
11. Scaling up demonstrations can be hazardous. It should never be attempted in front of an audience.
12. All demonstrations should be tested beforehand. Familiarity can breed a dangerous sense of complacency. Be on your guard. You are the responsible professional. All the benefits from the demonstrations are not worth one injury either to yourself or another.