In this lesson, students will use a circuit tester to determine whether objects are conductors or insulators. To begin the lesson, I model the process of creating a circuit tester on the document camera. As I work, I have students work alongside me. This ensures that every student has a functioning, properly constructed circuit tester with which they can complete the remainder of the lab.
To create a circuit tester, I guide students to build a simple circuit as they have done in previous lessons. I then ask them to disconnect the wire between one side of the bulb socket and battery holder. I have the students add a third wire to the battery holder so that there is an open space between the battery holder and bulb socket that can be bridged by the wire. To ensure that the tester is working, I have each student touch the wires together to ensure that their light bulb lights up.
All the materials used in this lesson are very safe for student use. Students may feel warmth from the battery or wire after they connect all of the wires in their circuit tester.
When each student has completed their circuit tester, I ask them to predict what will happen when we add a variety of objects to the circuit tester.
Next, I ask students to use their circuit tester to test a variety of objects (including straw, marble, pencil, etc.) for conductivity. One of the toughest things for students to manage is sorting out the test materials. To help students achieve independence in the classroom, I create and display a visual organizer showing all of the test materials.
The students connect the loose wires from the battery holder and bulb socket to each object and note whether the light bulb turns on. The students record their results on their conductors and insulators record sheet.
A video of the students testing objects in their circuit testers can be found here.
I conclude the lesson by adding new vocabulary words to our electricity glossary. I ask students to record the definitions for the terms conductor, insulator, and resistor.