Introduction to Circuitry

Purpose

Students practice decomposing problems by identifying the individual identity traits that are part of their complex identities and the individual components that complete a simple circuit.

As a reminder, this unit focuses on creating paper circuits. Before we move on and create our paper circuits, it's important to have a high level understanding of circuitry basics. These skills will help us design more complex circuits in the following lessons.

Vocabulary

Circuit

Battery

Current

Voltage

Resistor

LED

Conductive material

Materials

Toolkit for each student containing:

🙿 9 volt battery

🙿 3 volt battery

🙿 3 three alligator clips

🙿 300-330 ohm resistor

🙿 6 LEDs

🙿 print out of "My Complex Identity" worksheet

General:

🙿 Multimeter

🙿 Whiteboard or chart paper

What is a paper circuit?

A paper circuit is low-voltage electronic circuit that is created on paper or cardboard. Conductive copper tape, LEDs, and coin cell batteries are essential components of creating a paper circuit.

Simple, parallel, and series circuits are the main types used in the unit to create a paper circuit.

Step 1: Icebreaker (20-20 min)

Introduce the activity:
- “We all have different and complex identities that make experiences different for each person. This activity will allow us to explore how different parts of our identity resonate with us."
Pass out and explain the "My Complex Identity" worksheet.
- Review the identities and ask if anyone needs clarification on any of the identities listed.

3. Ask each participant to draw a line to match the list of identities on the left to the statements on the right. Each identity can be used more than once.

4. Lead a debrief discussion using the following prompts to get started:

What are 1-2 words to describe what this activity was like for you?
Are there any identities from the left hand column that you didn’t use? What do you think this means?
Are there any identities from the left hand column that you used more than others? What do you think this means?
Were any of the statements from the right hand column difficult to answer?
- Which ones? Why?
- What about the ones that were easy to answer?
Why do you think we had you do this activity?

Step 2: Introduce Decomposition

Decomposition means breaking a problem into smaller pieces.

We are going to learn about circuits by breaking the circuit into its smaller component parts.

Resources:

2 min - definition of decomposition

Step 3: Explain Major Circuit Parts

Battery

Circuits start with a power source. The power source for us today is a coin battery.

Current

The amount of electrons flowing in a circuit during a period of time. The rate of the flow is measured in amperes, known as Amps.

Voltage

You can’t have a current without an energy source pushing the electrons. Voltage is the amount of potential energy (or electrical pressure) in a source like a battery. Voltage is like water pressure: the higher the voltage, the more it can push electrons through a circuit.

LED

A Light Emitting Diode (LED) is a diode that emits light when a current flows through it. An LED has two terminals (or legs). The longer end is the positive end (+) and the shorter end is the negative end (-).

Conductive material

A conductive material is any material that allows electricity to flow from one point of the circuit to another point. Common conductive materials are wires made out of copper and copper tape. For example, when you want to light a lamp, you need a wire or a conductive material to run the current from the power source, usually a wall outlet, to the light bulb.

Circuit

All of these smaller component parts can be put together to create a circuit. A circuit is the path that charged particles take as they move from one side of a power source to another.

Q: Can you think of an example of where you might see a circuit in your house?

Step 4: Draw Circuit Diagram

Draw the major parts of a circuit (image below) but do NOT label them.

Invite individual students to label the diagram with the following terms: battery, voltage, current, LED, conductive path. If no one volunteers, fill in the terms yourself with prompting questions.

Step 5: Create Simple Circuit

1. Give each student [1] 9 volt battery, [1] 3 volt battery, [3] three alligator clips, [1] 300-330 ohm resistor, [6] LEDs.

2. Have students examine the materials. Make sure they recognize the following:

“+” symbol on the battery identifies the (cathode), which is the side of the battery with a positive charge
“-” or the other unmarked side of the battery identifies the (anode), which is the side of the battery with a negative charge
Amount of voltage on each of the batteries
One LED leg is longer than the other. The longer end is the positive end (+) and the shorter end is the negative end (-).

3. Ask the students to gather [1] LED and [1] 3V coin cell battery.

4. Ask the students to touch the positive terminal of the LED to the positive end of the battery and negative terminal of the LED to the negative side of the battery. The LED should light up! The students have created their first simple circuit.

5. Invite the students to explain how the simple circuit is working based on what they’ve learned.

Step 6: Introduce Resistance

Resistance

A resistor is an electrical component that limits or regulates the flow of electrons (current) in a circuit.

Each resistor has colored stripes to let you know how many electrons per second can flow through a circuit.

9 min - Detailed explanation of resistors

Color code calculator for resistor values

Create Simple Circuit with Alligator Clips

1. Demonstrate how to create a simple circuit using alligator clips, a 3V battery, and an LED. An alligator clip is a spring loaded metal clip attached to a wire that is used for making temporary electrical connections.

2. Have the students create their own simple circuit using the alligator clips.

Resources:

Reference video - how to create simple circuit with 3v coin cell battery and alligator clips.

Blow a Circuit!

Note to Facilitator: Make sure you have fresh batteries or batteries that you have tested on the multimeter for this activity.

1. Demonstrate blowing out a circuit with the 9 volt battery, two alligator clips, and the LED.

2. Ask students beforehand to watch the LED closely. It will light up for a moment and then burn out.

3. Invite the students to provide explanations for why the LED blew out.

4. Explain that the LED blew out because there was too much voltage flowing to it, therefore damaging the light.

Most LEDs require a forward voltage between 1.8 and 3.3 volts to properly light up. The amount of voltage required to properly light the LED varies by the color of the LED.

Resources:

Reference video- how to check a battery using a multimeter

Forward voltage of LEDs by color

Add a Resistor

1. Demonstrate the same circuit with a new LED and adding the 300-330 ohm resistor to the circuit.

2. Invite students to provide explanations for why the LED did NOT blow out this time.

3. Explain that the LED did not blow because resistance was added, causing only an amount of volagate the LED could handle to be delivered to the light.

Since most LEDs require a forward voltage between 1.8 and 3.3 volts, a safe rule of thumb for avoiding blowing out the LED light is to not use a power source (battery) that exceeds the voltage required.

Optional: You can also use Ohm's law to figure out what value of resistor you will need. This cheat sheet provides the typical forward voltage and current for different colors of LEDs.

Or handy calculator to figure out which resistor you will need for a simple circuit and parallel and series circuits

Resources:

6 min - Ohm's law

7 min - Ohm's law for parallel and series

Step 7: Explore Circuits

Give students free time to experiment with the materials and create their own circuits with the materials in their toolkits.

You can even encourage them to work with other people and combine materials to create a long chain of LEDs.

Step 8: Reflection

Review Decomposition - Breaking a problem into smaller pieces.

Discussion Questions

Q: How do you think you used decomposition today to learn about circuits?

Q: Did anyone have any problems making their circuits work? How did you overcome it?

Q: Did anyone help someone else learn? How so?

Q: What did it feel like when you got a circuit to work?

Q: Do you think you could teach someone else about the parts of a circuit and how to make a circuit work?

Q: Would you say you understand the parts of a circuit and how a circuit works better than when we started today?

Step 9: Appendix

My Complex Identity

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