Conductors and Insulators
Conductors and Insulators
| Students will be able to test a variety of electrical pathways using direct current circuits |
Preamble
The terms "conductors" and "insulators" are not introduced until the end of the session. This is in accordance with the literature (and my personal experience) that supports giving students a concept before giving it a label makes it easier for the students to remember both the concept and the label.
The class should be put in groups of three or four students.
| Will the electricity flow?
|
Equipment
Each group is given:
- 1 flashlight bulb
- 6 wires with crocodile clips
- 1 D battery in a holder
- a selection of about six objects. For example, a rubber band, a straw, a Popsicle stick, a paper clip, a pencil sharpened on both ends, a piece of string.
Challenge
Using the equipment you have been given, find out what kind of substances allow electricity to flow through them.
Before beginning you need to decide:
- How you will determine if a substance allows electricity through it
- How you will record your results
Please try to test about 15 substances.
Please write down and have ready to hand in:
- the names of your groups, the date, a diagram of the circuit you used, your results
- what type of substances allow electricity to flow through them. Can you give a category for the substances that allow electricity to flow?
Teacher: Circulate around the groups and engage them in discussion. In my experience, the students know exactly how to test that electricity flows through a substance, but tend to write their results in paragraph format. I try to encourage them to use tables.
I prefer to take the papers in from the groups at this point and look at them before coming to a whole class discussion.
| Whole Class Discussion after the Challenge |
Talk with the class about the idea that metals are conductors and other substances are not. Pencil "lead" is an exception and usually the only exception they find. Every class I have done this with have stated that metal "works" and other substances do not "work". This is a fun discussion about what "work" means and I have approached it differently every time according to exactly how the students have brought it up. Introduce the terms "conductors" and "insulators". Discuss the situations for which we need a conductor and those for which we need an insulator. I find this generally turns into a safety talk on electricity. The students bring up situations that they have experienced or they have been taught (such as taking toast out the toaster using a knife, or pulling a plug out by the cord rather than the plug itself). In this way, I manage to teach safety without the students really being aware of what I am doing. For my students this is better than a safety talk which they roll their eyes at.
Extension
- Research into semi-conductors and super-conductors may interest some students, or be a useful assignment for students who need more of a challenge.
- Ask students to find out if there are any plastics that conduct electricity.
Return to: inquiry lessons on electricity
