Name five things that we would not be able to do without using electricity. Explain why you think each of these things is important to us.
Learner dependent answer. Check that they have justified why each is important.
Systems to solve problems
- How can we use electric circuits to make useful devices and appliances?
- What happens to energy when we use electrical devices and appliances?
This unit is mostly application of what has been learnt before. Develop some of the science process skills: observe, design, evaluate and communicate. In order to develop thinking and motor skills, give the learners a project to build a model of a house that includes electrical wiring.
Using electric circuits
Electric circuits are used all around us, for example in lights in our homes, streets and shops. Let us imagine our world of today without electricity!
Aworld without electricity
Let the learners work in groups of 2-4. There are no specific right or wrong answers here, except if the responses do not have anything to do with electricity. The learners are giving their perceptions and opinions. The activity provides a starting point for learning about the use of electric circuits.
INSTRUCTIONS:
-
Write a short paragraph of how our world would be like without electricity.
-
Describe the three things that will be the biggest disaster for you if there was no electricity.
-
Would there be any advantages of not having electricity? Discuss this with your classmates and write your answer below.
-
Your group should now compare the advantages and disadvantages of electricity. What is the group's conclusion, a yes or no for electricity? Write down your group's reasons for saying yes or no.
Electric circuits are often used to solve a problem where we need energy. A battery or mains supply is a source of energy. The energy is transported to a device or an appliance using electric wires. The device or appliance dissipates the energy. The effect could be light, sound, heat or movement. In other words, the device gives off energy in the form of light, sound, heat or movement.
A system is something that consists of different parts working together to form a whole. In an electric system, there is an input (energy) and an output (resulting in light, heat, movement, or sound). Let's look at some examples of electric systems where we use the output energy to do something useful.
Energy is transferred or dissipated, not transformed. Energy is defined as the capacity to do work, so it does not change from one form to another, but it can be transferred.
Electric circuits influence our lives
INSTRUCTIONS:
- Look at the photos or sketches below.
- Name the appliance or device.
- Say what it is used for and what the energy is transferred to (light, sound, heat or movement)? In some cases it might be more than one thing!
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
 (Scalextric http://www.flickr.com/photos/magickevin/7161372557/) |
Name: Use: Energy transferred from _______ energy to ____________ |
 |
Name: Use: Energy transferred from _______ energy to ____________ |
This is quite a long activity with many examples, but it leads into the Technology Project a bit later where learners have to use an electric circuit to produce light, movement, sound or heat. This activity will act as a stimulus for ideas for the project.
Each of the examples in the previous activity uses an electric circuit to provide us with energy where we need it, whether it is light on the street, sound for our radio, or heat in a building. Or even in some toys and models such as a car racing game, or model electric train set! We can say that electrical appliances can solve problems for us. They are able to transfer electricity so that another useful form of energy is released.
Be an electrical engineer or technician
At this point learners have learnt adequate concepts related to electricity to give them a Technology Design project to do. They can work individually or in teams of 3-4. Ideally though, each learner should design and make their own system to fully engage with the task. Learners will apply what they learnt by first discussing, designing and drawing a plan of how to use a circuit to produce movement, light, sound or heat. It is generally more difficult to produce heat energy using cells, but this can be explored by learners if they feel they are up to it. Then they will implement their design and make the structure and then present it to the class. Communication is a vital skill and forms part of the Technology Design Process. Communication can be written or verbal, but in this case learners must verbally present their designs to the class. The model that learners build need not be to scale. Possible designs include a steady hand game, a house (encourage them to have more than one room or a doorbell system), a lighthouse, or some type of toy which produces sound or movement. Encourage learners to use everything that they have learnt about electric circuits and include different components, such as switches.
Let's say you want to become an electrical engineer or electrician. One of the things that you will be doing is to design systems that use circuits to solve problems for people, whether it is the wiring in a house, an alarm bell, a lighthouse on the coast, or constructing toys which use electrical energy to work.
Design, make and present a system using a circuit
DESIGN BRIEF:
You are an electrical engineer and you need to come up with a design for an electrical system to solve a problem. You need to design and make a system that uses a circuit to produce movement, light, sound or heat. Write a Design Brief where you identify what you are going to make and why it needs an electric circuit.
INVESTIGATE:
The next step in the Design Process is to do some research about the instrument that you are going to make. You can use books and the Internet to do your research.
Answer these questions when doing research about your electrical system:
-
How is this system normally made?
-
What components does it need?
-
What type of energy will be produced from electrical energy?
-
Why do people need this system? What problem does it solve?
DESIGN:
Now that you know a bit more about the system you want to make you need to design how you are going to make it.
Your system has the following specifications:
- The system must make use of an electrical circuit.
- The system must produce either movement, sound, light or heat.
- The circuit must make use of some of the components that you have learnt about, such as batteries, light bulbs, switches, buzzers, wires, etc.
- Your system must make use of a switch to turn it on and off.
Your system has the following constraints:
- You must make it in class.
- You cannot get an adult electrician to design your project for you! You must come up with your own design.
- Your system is not life sized, but must be a model.
Answer these questions:
-
What materials will you need to make it? For example, which electrical components will you need? Which other materials will you need, such as a cardboard box to put the system in, adhesive tape or Prestik, drawing pins, or paint to paint the box?
-
What tools will you need to make it? Such as pliers to cut the wire, scissors to cut cardboard. Make a list and collect some of these items from home, or else ask your teacher if he/she has any.
-
How many batteries will you need for your circuit?
-
Where will you place the switch? What type of switch are you going to make?
Now you need to draw some designs for your system. Use scrap pieces of paper to do your first designs. Once you are happy with your design, use the space below to draw your design. Label your drawing showing what materials you are going to use for the different parts.
When you are making your system you might get better ideas to improve the design as you test it out to see if it produces the required output. So come back afterwards and draw on the bottom half of the page; show what you really decided to make.
MAKE:
Now make your system! After you have all finished making your systems, perhaps go around and look at what others have done. Ask each other questions to see what you can learn from others. You will also have to present your project to the class so use this time to get ideas about how to present your idea and product that you made.
EVALUATE:
Before we get on to presenting the projects, you need to evaluate your own project. You can then use this evaluation in your presentation to show others what worked and did not work.
-
Does your system look like your initial design?
-
Does your system produce a movement, sound, light or heat?
-
Where would people use the system you designed to solve a problem in our daily lives?
-
Is there anything you might do differently to improve your design?
COMMUNICATE:
An engineer needs to be able to present their designs to show others what they have come up and communicate their ideas. Engineers can present a written report and hand in their design drawings. But, often an engineer will need to present the design and project by speaking and giving a verbal report.
Your last task in this Design project is to present your system to your class.
These are your instructions:
- Present an oral report to the rest of the class to tell them about the system that you built.
- You must have your system with you in the front of the class and show how it works.
- You must explain the electric circuit that is used and what type of energy is produced.
- Tell the class how your system could be used by people and why they might value your design. For example, could it be used in a house by people or maybe it could form a new toy on the market?
- Lastly, tell the class what you learnt by doing this project and anything that you found tricky or difficult or that you might change if you had to do it again.
Each learner must be assessed for the actual system that they built and their designs, drawings and planning. And each learner must be assessed in the way that they present their project orally. Pay special attention to the learner's ability to project their voice and engage with the class, their ability to explain what they have done and whether they answered all the questions outlined in the instructions above.
- Electric circuits solve problems like getting electric lighting for example.
- There are many instances in the world around us where electric circuits are used, such as street lighting, alarms, electric gates, traffic lights, fans and heaters, some models and toys.
Jojo builds an electric circuit that includes a bulb and battery for his bedside table so that he can read at night, but the bulb does not light up. List three things that could be wrong.
The battery could be placed the wrong way, the battery is flat, there is a break in the connection somewhere, one of the wires is not connected properly or is broken, the bulb may have `blown', meaning the filament inside the bulb is broken.
Jojo does not want the battery in his bedside light to run out of energy. What could he do?
He can include a switch to turn it on and off to save the battery.
List three electrical devices that use energy from a battery.
Torch, cellphone, walkman, etc.
List three electrical devices that use energy from a mains supply.
Microwave, stove, iron, hairdryer, fridge, etc.
Draw an electric circuit diagram for the system that you designed and made in the Design Project.
