Circuit breakers
View Sequence overviewStudents will:
- understand that batteries store chemical energy.
- model the way a current transfers electrical energy around a circuit.
- discuss the way electrical energy can be transformed into light energy, heat energy, or sound energy.
Students will represent their understanding as they:
- model the movement of energy around an electrical circuit.
- describe the transfer and transformation of energy in an electrical circuit.
- participate in and contribute to discussions regarding the advantages and limitations of modelling.
- use the TWLH chart to consider what they have learned.
In this lesson, assessment is formative.
Feedback might focus on:
- Are students able to describe the batteries as storing chemical energy?
- Are students able to describe how electrical energy travels around a circuit?
- Are students reasoning and making justifications based on evidence they have collected?
Whole class
Class science journal (digital or hard copy)
Stripping pliers (to strip the insulation from the wires if required)
Materials to create a word wall
To build the bicycle chain model:
- Bicycle (with chain)
To build the delivery model:
- Blu tack
- 8-10 toy cars
- 2 sheets of A4 paper
Each group
1 x 1.5V AA battery
1 x 1.5V battery holder
1 x light bulb holder
1 x 1.5V light bulb (+ spares)
2 x 10 cm length of insulated wire, with the ends stripped of insulation (+ spares)
NOTE: If no electrical equipment is available, the Circuit Construction Kit on the PHET website can be used.
Each student
Individual science journal (digital or hard-copy)
Lesson
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkRe-orient
Revisit the effects of a blackout on people. This can be done by switching off all the electrical appliances/lights in the classroom/school at the safety switch.
Students can recreate the circuits they built in Lesson 2 to provide light in the room.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkIdentifying and constructing questions is the creative driver of the inquiry process. It allows students to explore what they know and how they know it. During the Inquire phase of the LIA Framework, the Question routine allows for past activities to be reviewed and to set the scene for the investigation that students will undertake. The use of effective questioning techniques can influence students’ view and interpretation of upcoming content, open them to exploration and link to their current interests and science capital.
When designing a teaching sequence, it is important to spend some time considering the mindset of students at the start of each Inquire phase. What do you want students to be thinking about, what do they already know and what is the best way for them to approach the task? What might tap into their curiosity?
Read more about using the LIA FrameworkElectrical sources
Pose the question: Where does the electrical energy for a circuit come from?
If students haven’t asked this question themselves in the TWLH chart, add it to the list of class questions and discuss that answering this question will be the centre of today’s investigation.
Use students' circuits to prompt discussion.
- What does each part of the circuit do: the light bulb? The wires? The battery?
- In Year 5 you learned light is a type of energy. Where does the light bulb get the energy to produce light?
- Common answers: the wires; electricity; the battery.
- What is the energy source in the circuit? What does the energy source do?
- The battery transfers energy to the wires.
- Where does the battery get its energy from?
- There is nothing connected to the battery, so the energy must be stored inside it.
Discuss:
- the battery in the circuit is full of chemicals that store chemical energy.
- the chemicals in the battery produce small particles called electrons.
- when the battery is connected into a circuit, it ‘pushes’ the electrons around the circuit.
- the movement of electrons along the wires is called the current.
- the moving current transfers the electrical energy to the bulb.
Transfer and transformation of energy
Energy can be transferred or transformed, but it cannot be created or destroyed.
Energy can be transferred (passed from one thing to another) or transformed (changed from one form of energy to another form), but it cannot be created or destroyed in a system. If we know where to look, and how to measure it, we can add up all of the energy: the total amount never changes.
In a circuit, the battery contains chemicals that react with each other to transform chemical energy into electrical energy. Batteries are designed to transform energy only when the positive and negative poles of the battery are connected to each other by a material that allows electrons to flow, such as a metal wire.
Energy can be transferred (passed from one thing to another) or transformed (changed from one form of energy to another form), but it cannot be created or destroyed in a system. If we know where to look, and how to measure it, we can add up all of the energy: the total amount never changes.
In a circuit, the battery contains chemicals that react with each other to transform chemical energy into electrical energy. Batteries are designed to transform energy only when the positive and negative poles of the battery are connected to each other by a material that allows electrons to flow, such as a metal wire.
Alternative conceptions
What alternative conceptions about electrical energy might students hold?
Source-sink model (non-scientific idea)
Students might believe that batteries push something to the light bulb, which is transferred through the wire. This might mean that they only believe one wire is needed, whereas a complete circuit is required for the battery to operate and for the electrons of the circuit to move in a single direction. This conception is reinforced by home appliances only need one cord to connect to mains power, however, the cord has several wires embedded to complete the circuit.
Consumption model (non-scientific idea)
Students correctly identify that two connection points are required. But they think that something comes out of the battery, which is partially (or totally) used up by the light bulb so less returns to the battery. The number of electrons in each wire does not change, although the electrons themselves move. What is consumed is the chemical energy in the battery, which is released when hooked into a circuit and converted (transformed) by the bulb into light (and sometimes heat).
Clashing currents model (non-scientific idea)
Students might think that things flow from each end of the battery and meet in the devices on the circuit. The collision of these two streams of things creates light (and sometimes heat). This ‘clashing currents’ model can mean that students correctly identify that two connection points are necessary, but does not reflect the scientific understanding that the electrons of the circuit move in the direction from the negative terminal of the battery to the positive. Unaware of positive and negative terminals, students might be able to draw a circuit but not connect the wires in such a way as to make the light glow. One reason is that they might not realise that the electrons only flow in one direction from negative to positive terminals.
Source-sink model (non-scientific idea)
Students might believe that batteries push something to the light bulb, which is transferred through the wire. This might mean that they only believe one wire is needed, whereas a complete circuit is required for the battery to operate and for the electrons of the circuit to move in a single direction. This conception is reinforced by home appliances only need one cord to connect to mains power, however, the cord has several wires embedded to complete the circuit.
Consumption model (non-scientific idea)
Students correctly identify that two connection points are required. But they think that something comes out of the battery, which is partially (or totally) used up by the light bulb so less returns to the battery. The number of electrons in each wire does not change, although the electrons themselves move. What is consumed is the chemical energy in the battery, which is released when hooked into a circuit and converted (transformed) by the bulb into light (and sometimes heat).
Clashing currents model (non-scientific idea)
Students might think that things flow from each end of the battery and meet in the devices on the circuit. The collision of these two streams of things creates light (and sometimes heat). This ‘clashing currents’ model can mean that students correctly identify that two connection points are necessary, but does not reflect the scientific understanding that the electrons of the circuit move in the direction from the negative terminal of the battery to the positive. Unaware of positive and negative terminals, students might be able to draw a circuit but not connect the wires in such a way as to make the light glow. One reason is that they might not realise that the electrons only flow in one direction from negative to positive terminals.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkThe Investigate routine provides students with an opportunity to explore the key ideas of science, to plan and conduct an investigation, and to gather and record data. The investigations are designed to systematically develop content knowledge and skills through increasingly complex processes of structured inquiry, guided inquiry and open inquiry approaches. Students are encouraged to process data to identify trends and patterns and link them to the real-world context of the teaching sequence.
When designing a teaching sequence, consider the diagnostic assessment (Launch phase) that identified the alternative conceptions that students held. Are there activities that challenge these ideas and provide openings for discussion? What content knowledge and skills do students need to be able to complete the final (Act phase) task? How could you systematically build these through the investigation routines? Are there opportunities to build students’ understanding and skills in the science inquiry processes through the successive investigations?
Read more about using the LIA FrameworkModelling electrical flow
Discuss:
- how models can be used to show how energy can be moved and transferred from one object to other objects.
- how models can show some things well but may not be able to show other things as well. Use an example that is known by students to illustrate this, for example:
- A model car shows the shape and colour of a car, but does not have the same engine.
- You can build cars using Lego or in Minecraft, but it is difficult to have rounded edges like real cars.
- Plastic food can show the colour and shape of the food but not the smell.
Demonstrate both of the following models and compare them with the students' electrical circuits. Encourage students to use reasoning or provide evidence to support their comparisons, such as "I think the ... model is better because...", or "I think model ... is not very good at showing ... because ..."
A person pushing on the pedals of a bicycle (battery) transfers their energy to the chain. This pushes the chain (current) around the loop. The moving current transfers/moves energy from the pedals to the wheels (light bulb) almost instantaneously. The chain (current) keeps being pushed evenly and does not get lost. If the brakes are put on, the wheel (light bulb) stops moving.
Discuss the limitations of this model:
- If the rider stops pedalling the bike, the wheel keeps moving. This can suggest that the light will keep working if the battery is flat.
- If a circuit adds another wheel/gear/bulb, the person has to push harder to make the chain go around. Batteries cannot push harder.
In this model, moving toy cars are used to represent a current. The toy cars will "transfer" the energy from the battery to the lightbulb.
Arrange the toy cars in a circle (like a circuit). Draw a battery on one sheet of paper, and a light bulb on one sheet. Place the battery on one side of the car circle, and the light bulb on the other side. Ask students to move the toy cars around in a circle. As they move through the battery, students place a small piece of Blu Tack (energy) on the car. The toy car moves around the circuit to the light bulb. Once there, the Blu Tack energy is transferred to the light bulb. The toy car then moves back to the battery to have more energy transferred onto it.
Discuss the limitations of this model:
- Students may assume that once the energy/Blu Tack is gone, the cars will not move. Remind students of the bicycle chain model where the pedals push the current around the circuit.
- Students may assume that the Blu Tack energy is ‘used up’ at the light. Remind students that the Blu Tack changes/transforms into light energy.
Invite students to share examples of a device or toy that did not work because the battery was flat. What happens when the battery goes flat? Where did the energy go? How do rechargeable batteries get their energy back?
Discuss:
- how the amount of chemicals that react in the battery is limited.
- when batteries have all passed on their chemical energy, there will be no more electrical energy produced.
- this means there will be no more ‘push’ on the electrons.
- if the current stops moving, it cannot transfer the electrical energy.
- recharging a battery involves 'pushing' the electrons in the opposite direction and storing them as chemical energy.
In the bicycle chain model, a flat battery is similar to putting on the bike brakes. In the delivery model, a flat battery means there are no students to push the toy cars around.
Support students, through questions, to conclude that the energy does not 'disappear’ but rather is changed into other types of energy.
- What type of energy does the battery store?
- What happens to the energy in the chemicals?
- The chemical energy changes/transforms into electrical energy in the wires; pushes electrons around the circuit; makes the current transfer electrical energy in the circuit.
- What happens if there are no chemicals left to react in the battery?
- The electrons do not move; the current does not take electrical energy around the circuit.
Modelling electron flow
Developing and testing a model of the transfer and transformation of energy enables students to explore their understanding of these concepts.
Developing and testing a model of the transfer and transformation of energy enables students to explore their understanding of these concepts. Comparing two models that outline the flow of electricity allows students to ask, “what is the same and what is different?”. Identifying similarities in the models allows students to identify the key characteristics of energy (a property) and electron flow. Identifying differences between the models allows students to question the importance of these features in the model.
Developing and testing a model of the transfer and transformation of energy enables students to explore their understanding of these concepts. Comparing two models that outline the flow of electricity allows students to ask, “what is the same and what is different?”. Identifying similarities in the models allows students to identify the key characteristics of energy (a property) and electron flow. Identifying differences between the models allows students to question the importance of these features in the model.
The Inquire phase allows students to cycle progressively and with increasing complexity through the key science ideas related to the core concepts. Each Inquire cycle is divided into three teaching and learning routines that allow students to systematically build their knowledge and skills in science and incorporate this into their current understanding of the world.
When designing a teaching sequence, it is important to consider the knowledge and skills that students will need in the final Act phase. Consider what the students already know and identify the steps that need to be taken to reach the level required. How could you facilitate students’ understanding at each step? What investigations could be designed to build the skills at each step?
Read more about using the LIA FrameworkFollowing an investigation, the Integrate routine provides time and space for data to be evaluated and insights to be synthesized. It reveals new insights, consolidates and refines representations, generalises context and broadens students’ perspectives. It allows student thinking to become visible and opens formative feedback opportunities. It may also lead to further questions being asked, allowing the Inquire phase to start again.
When designing a teaching sequence, consider the diagnostic assessment that was undertaken during the Launch phase. Consider if alternative conceptions could be used as a jumping off point to discussions. How could students represent their learning in a way that would support formative feedback opportunities? Could small summative assessment occur at different stages in the teaching sequence?
Read more about using the LIA FrameworkTransfer and transformation
Invite students to draw their own model of a circuit and how the energy is transferred between objects. Add labels and descriptions of what is happening at each stage.
- I have a question about this part of your circuit. Why have you included this?
- Can you describe how your circuit works for me?
- I wonder how your circuit is the same/different to ____________.
- I wonder what would happen if _________.
- I have a question about _____________.
- I wonder why ________________.
- What cause _______________?
- How would it be different if ______________?
- What do you think will happen if _____________?
Compare the students’ models as a class, carefully selecting models that are different but illustrate the key idea of transfer of energy. Remind the students of the limitations of the bicycle chain model and the delivery model. Ask students to determine one limitation of the models they have drawn.
Introduce the term ‘transform/transformed/transformation’. Contrast this term with ‘transfer’ (passing energy from one object to another). Discuss the meaning of ‘transform’ and provide some examples, such as:
- Cooking a cake mix transforms it into a cake.
- Caterpillars transform into butterflies.
- Cars transform petrol into movement.
- Light bulbs transform electricity into light and heat.
- A battery transforms chemical energy into electrical energy.
Add the terms ‘transform’ and ‘current’ to the class word wall/glossary.
- transform: changes the type of energy from one form to another
- current: the flow of electrons around a circuit
Ask students to revise their drawn model to include explanations of the energy transformations that are occurring.
Reflect on the lesson
You might:
- re-examine how models can be used by scientists to explain what happens in the real world.
- update the TWLH chart by adding what students have learned (L) and the evidence/observations that show how (H) they now know that. For example: “I learned that models can explain how electrical current moves around a circuit. I know this because my models shows .... I learned that models have limitations. My model does not show...“