Teachers TryScience

How does electricity flow? Designing a strand of lights.

Jan 05 2012

Source: Tess

Summary Information

Keywords:

Parallel circuit, series circuits, simple circuit, closed circuit, open circuit, current, atoms, electricitty

Topic:

Physical Science

Workplace Skills:

Problem Solving

Investigation Design

Discussion

Estimated Time Required:

less than 1 hour

Target Grade (Ages):

Grade 5 (Ages 10-11)

Grade 6 (Ages 11-12)

Diversity Indicators:

Students in grades 3 through 6.

Tab Wrapper

LESSON

Goals and Prerequisites

Goals:

By the end of this lesson students should be able to design a string of lights that is most efficient. Electricity should flow through the lights in a parallel circuit. If one bulb is removed, the others should stay lit. Students should be able to verbalize the reasoning behind this.

Prerequisites:

Students should have some knowledge about static electricity. They should know that electricity can take more than one form. They should have an understanding that electricity is a form of energy and current electricity is a form of energy that flows through wires.

Instructional Objective(s)

Students will:

identify ways to create a closed circuit
describe how current electricity flows
construct a series circuit
construct a parallel circuit
identify various ways to open a circuit

Instructional Resources

Background:

Background Information:

Everything is made of atoms, including humans. An atom looks like the sun with the planets spinning around it. The center is called the nucleus. It is made of tiny protons and neutrons. Electrons move around the nucleus.

When an atom is in balance, it has the same number of protons and electrons. It can have a different number of neutrons. Electrons stay in their shells because a special force holds them there. Protons and electrons are attracted to each other. Protons have a positive charge (+) and electrons have a negative (-) charge.

Moving electrons are called electricity. Electricity travels in closed loops, or circuits (from the word circle). It must have a complete path from the power source through the wires and back.

If a circuit is open, the electricity can’t flow. When we flip on a light switch, we close a circuit. The electricity flows through the light and back into the wire. When we flip the switch off, we open the circuit. No electricity flows to the light.

The current in a series circuit goes through every component in the circuit. Therefore, all of the components in a series connection carry the same current. There is only one path in a series circuit in which the current can flow.

In a parallel circuit current can flow through each of the bulbs without first having to flow through any others. If any of the bulbs fail the others will still work as current can still flow through the rest of the circuit.

Materials:

Light bulbs, string of lights, batteries, wires, light bulb holders, battery holders, student lab sheet, rubric

Procedure:

Motivation: “I have bought lights numerous times and found that if one light bulb goes out, the others go out too. This is a problem because I have to find out which bulb is causing the problem or I have to go out and buy new strands. I was wondering if you could help me design a strand that would be more efficient.”

Procedure:

Motivation.
Tell them that a good scientist or engineer keeps a record of what has worked and hasn’t worked so that they can repeat the activity if needed. We will record our findings on a lab sheet.
Inform the students that engineers and scientists also communicate and often work as a team. This helps them to achieve their goals.
Distribute the bulb (a part of the strand) and battery. Challenge the students to light the bulb.
Students share their setups.
“What do the setups have in common?” Discuss circuit and complete and incomplete circuit. Elicit that they were able to light the bulb because there was a complete circuit.
How can we add another light to our circuits?
Design a new strand that has more than 1 bulb.
What happens when I light bulb is removed or damaged? Why? Discuss with your group.
Share as a class.
Elicit that the circuit is opened and electricity can no longer flow in a complete circuit.
So, we need to design a strand of lights in which bulbs can stay lit even though one bulb is out.
Discuss some options with your group.
Try them out.
Students share their circuits with other groups.
Great! Can you explain your reasoning as to how your group arrived at that design idea?
Explain that what they have just designed is called a parallel circuit meaning that current can flow through bulbs without having to flow through all of them. If one bulb fails, the others can still work.
If you were to purchase a strand of lights, what would the strand be like? Why?

Extensions

Students will create a village out of small cardboard boxes. The houses, and office buildings in the village will have lights that encompass series and parallel circuits. The students will design street lights and a “power plant”. The town will be built on a budget. Students will create a power point presentation explaining how electricity flows from the town power plant to the buildings.

Assessments and Rubrics

Circuit Rubric

Category

Teamwork

All tasks were not completed. 2 or more students did not follow assigned tasks. Tension within the group.

Some tasks were completed. Some ideas were incorporated into design and construction.

Most members completed their tasks. Most ideas were incorporated into design and construction.

All members completed their tasks. They listened to each other’s ideas and incorporated them into design and construction.

Scientific Thinking

No evidence provided to construct explanations.

Some evidence provided to construct explanations.

Much evidence is provided to construct explanations.

Uses evidence to construct explanations. Uses concepts to explain a variety of observations and phenomena.

Scientific Investigation

Student did not complete an experiment , design or observation.

Some parts of the experiment, design and observation were completed

Most of the experiment, design and observations were completed.

Demonstrates scientific competence by completing an experiment, a design and observation.

Scientific Communication

Data was not represented and facts were not used to support conclusions.

Some data and facts were used to support conclusions.

Most of the data was represented and most facts were used to support conclusions.

Represents data and results in multiple ways. Uses facts to support conclusions.

Name____________________ Class__________ Date_________

Essential Question: How does electricity flow?

1. Work with your group to try to light the bulb using the materials.

2. Draw your setup.

3. Study the drawings. Predict in which setups the bulb will light. Circle them.

4. Why do you think the bulb will light up in the setup? ________________________________________________________________

5. Add another light bulb to your circuit.

6. Draw your design.

7. What happens when 1 bulb is removed? Why does this happen?_________________________________________________________

8. How can your group arrange the lights so that if one bulb goes out the others stay lit? Draw your setup.

9. Which type of lights should I buy in the future? Why?_____________________

External Resources

Smart Exchange lessons on electricity.

www.neok12.com/electricity

Credits

Tess Vannata P.S. 97Q (STEM Teacher)

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Comments

excellent lesson plan for

excellent lesson plan for making school children aware of electricity flow