TEACHER’S GUIDE

Materials:

For each pair of students:

2 Student Activity Sheets for Learning Experience 16 (Please see PDF)

4 “D” batteries

4 assembled battery holders

Teaspoon salt, sugar, baking soda, vinegar

Bulb holder

#48 bulb

5 medicine cups

2 Fahnestock clips

2 15 cm. pieces #20 bare copper wire

3 5 cm. pieces #20 bare copper wire (to hook batteries together)

Toothpick

For the class:

3 teaspoons

Wire cutter

Warm water

Tap water, lake water, milk, coffee, orange juice, and liquid soap

Preparation:

Read the background information on liquids conductivity in the Electrical Circuits Teacher’s Manual. (Please see PDF) To create the salt, sugar, and baking soda solution, students should begin with a leveled teaspoon of each substance. Gradually, the substance is to be added to the warm water in the medicine cup. Stir into a solution with a toothpick. Liquids that contain a noticeable amount of acid, bases, or salts are good conductors of electricity. Liquids that contain only a trace amount of acids, bases, or salts are poor conductors of electricity, but may conduct electricity if the voltage is high enough. Stress to students that they should not swim in a pool or lake during lightning storms because they contain trace amounts of acids, bases, and/or salts. Also, stress that 110 volt appliances should not come into contact with household plumbing, water, or other liquids.

Basic Skills Development:

Discussing

Following Directions

Comparing

Predicting

Observing

Evaluation Strategy:

Given a group of several liquids, students will be able to identify which liquids are conductors and nonconductors using a physical test.

Vocabulary:

liquid

conductor

non-conductor

insulator

solution

Objective: Students will predict, test, and determine if various liquids are conductors and non- conductors.

What liquids are good conductors of electricity?

Students should construct a liquid circuit tester shown on the activity sheet for Learning Experience #16 of the Electrical Circuits Student Activity Book. (Please see PDF) Each medicine cup is to contain one of the solutions to be tested. Students are to place the Fahnestock clips in the solutions. For best results, the flat sides of the Fahnestock clips should face each other. Students are to complete the data chart on the activity sheet and answer the questions that follow it. Remind students to clean Fahnestock clips between the tests of the different solutions.

Discussion Questions:

How did you decide which liquids conduct electricity?

What similarities are found among the liquid materials that conduct electricity?

What similarities are found among the liquid materials that do not conduct electricity?

Which liquids produced results different from what was predicted? How could this be explained?

What other liquid materials, not tested, might be predicted to be conductors or nonconductors?

What safety rules should be observed when involved with liquid conductors?

Repeat this learning experience using liquids brought in from home. Some interesting liquids to try are: tap water, lake water, milk, coffee, orange juice, and liquid soap. Corrosive, caustic, and poisonous liquids should not be used.

Activity Sheet Answers

Vinegar – No

Salt water – Yes

Baking Soda – Dim

Sugar water – No

For the accompanying Electrical Circuits Student Activity Book, please refer to the PDF found here. (Please see PDF)