Lesson Plan Industry Sector
Transportation

## **Fabricate a simple electrical switch (updated) by Ramon C. Iniguez

### Lesson Plan Overview / Details

Students will apply their knowledge of insulators and conductors to fabricate a simple switch for a DC circuit.

Two periods
100 Minutes

### Objectives and Goals

• Recognize conductors and insulators
• Use common conductive and insulating materials found around the shop to fabricate a simple switch for a DC circuit

### Activities in this Lesson

• To introduce the lesson, I turn the classroom lights on and off several times until I have the student’s attention. Then I ask the students if any one can explain how the switch turns the lights on and off.

Once the students share their explanation, I also ask the students if all switches work the same.  The majority will answer no.  Give students time to explain why not.

I ask the students to share their knowledge of the different types of switches with the class. I pass around several examples of switches such as toggle switches, rocker switch and momentary switches for the students to see.

After the discussion I tell the students that today they will make their own switch.

• To start the lecture, I ask students if they know what materials an electrical wire is made of.  Eventually, most will say metal and plastic, or something similar.

I explain that the wire is classified as a conductor and that the plastic is classified as an insulator. I further explain that a conductor allows electricity to pass through it while an insulator does not.

Examples of conductors are metals and liquids.

Examples of insulators are plastics, rubber and wood.

At this point I ask the students if they remember the parts of the atom. I draw the part of the atom on the board as they mention them. I explain that conductors have electrons at the outermost valence that are free to move from one atom to another while insulators have electrons at the outermost valence that can not move from one atom to another.

Use the attached animation to help you explain the movement of the electrons between the atoms.

Class activity:

Ask the students to locate conductors and insulators that are around their seats and or that they have on their position. Then ask them to name items that are conductors…next, ask them to name items that are insulators.

• Introducing the lab - Group Work

Show students examples of student work (see attachments) so that they have a model to base their idea to. Once the students have a clear understanding of the expectations, divide the class into groups and have them search the shop, or designated area, for insulators and conduction to fabricate their switch. Give each group two six-inch lengths of wire to attach to their switch. These wires will then be connected to a light and battery to test the function of their switch.

Caution!

Discuss battery safety, and any other safety issues that you find important, before allowing students to connect their switch and light to the battery.

Note: Before releasing the students to look for their materials, tell them that you want to see their materials before they start fabricating their switch in the event they have materials that you don’t want them to use.

• Samples of student work-switch.ppt [ Download ] Power point contains student work samples
• After the groups are completed and assessed, have a representative of each group explain their switch design. After all groups have presented their designs, ask if any group would redesign their switch.

### Assessment

Assessment Types:
Projects, Demonstrations, Observations,

Assessment:

Visit each group and have them explain their plan to you; provide the students feedback and guidance. Be prepared to provide students with additional items that my not be available in the shop such as tape, paper clips staples etc.

Checking the switch for continuity:

Have the students use a Digital Multimeter (DMM) to test the function of their switch. Set up the DMM for those students that don’t have experience with the DMM and explain that a low ohm reading means that they have good continuity (electricity will flow easier through the circuit) and that a high ohms reading means that the switch has poor continuity (electricity will not flow easily through the circuit if at all). Have students repair their switch if high resistance or no continuity is determined.

Final assessment:

Caution!

Remember to discuss battery safety, and any other safety issues that you find important, before allowing students to connect their switch and light to the battery.

With the switch open (off) connect a DC light and battery to the wires that the students connected to the switch. Have the students close (turn on) the switch; the light should turn on brightly at this point indicating that they constructed a functional switch.