Hello scientists.

My name is Mr. Wilshire, and today we are going to be looking at switches.

Let's dive into our lesson.

Our outcome today is to explain how a switch is used to open and close a circuit.

Hmm.

Here are some keywords.

I'm gonna say them.

I'd like you to repeat them after me.

My first word, switch.

My next word, control.

Next up, circuit.

Then we have complete.

And finally, incomplete.

Well done everybody.

Now here are some of the definitions for those keywords.

You can pause the video here and have a read through and have a think if there are any that you're not too sure about.

Hopefully over the course of the lesson, as we use these words in our slides, you'll get an idea for what they mean and how we can use them.

So let's dive in.

The first part is called understanding switches.

Now, what do all of these images show? Pause the video here and have a quick discussion.

What can you see in each image? So I wonder what you discussed there.

Well, let's have a look.

These are a selection of switches.

These are all types of switch.

Have a chat.

What would you use each one of these for? Have a look at each picture carefully and decide where you would usually see them.

Well, all of these are to control different appliances and devices that need electricity to work, such as by turning them on and off.

The top one there or that one is a volume button and a programme button.

Ah, it looks like it's from a television.

Then there's a silver one with two switches.

That's definitely a light switch.

Next up, oh, there's a turbo button on that one.

That one could be from a boiler perhaps.

Then after that there's a switch with a little light on it as well.

I wonder what appliance that's turning on? Could be a lamp, for example.

After that, there's a dial there which switches the programme that you have on a washing machine.

Finally, you've got a red switch there with a little bulb on top to tell us that it's on.

That is going to control some different appliances in either the kitchen or the bathroom.

Switches are used to control a circuit.

Here is an example of a switch.

There's an on and there's an off.

For electricity to flow around a circuit, there must be a complete loop from the electricity source.

Then that goes through the components and back to the electricity source.

Switches can break a circuit by making a space between components where the electricity can't flow anymore.

This breaks the loop and stops the flow of electricity because the circuit is incomplete.

I wonder if you've seen a switch a little bit like that before? Maybe it turns something on or off.

Switches usually have two positions.

They're open and closed.

You can see two examples there.

One is open and one is closed.

Just looking at the switch like that it's quite hard to tell which one is which.

You would have to make sure that you put it the right way up.

Maybe have a little look at some light switches that are around your school or maybe at home.

Maybe you'll see if they are a particular way up and if they will turn things on or off if they're the wrong way up.

When the switch is open, this makes a gap and the circuit is incomplete so electricity can't flow through it.

When the switch is closed, the circuit is complete and electricity can flow through it.

Yeah, I can see there's definitely a break in that loop there isn't there? So a switch is something that breaks it.

In electrical circuits, switches are used to turn bulbs, buzzers and motors on and off.

Alex here says, "When the switch is open, devices will not work.

They will be off." Sofia says, "When the switch is closed, devices will work.

They will be on." Remember, a circuit needs to be a complete circuit.

You can trace your finger all the way around it can't you, like in a circle, and when a switch is applied, that causes a break in the circuit like that.

So, when it's open, it's going to be off.

When it's closed, it's going to be on.

So pause here and think, what do switches do? Do they produce light? Do they power circuits? Produce noise or control circuits? Pause the video and have a think.

Hopefully you said that they control circuits because they've got the power to turn it off and on.

They don't really produce light.

They don't have electricity in them and they don't produce noise by themselves.

Stop and think again, how do switches stop electricity flowing around a circuit? Do they make a barrier which the electricity can't flow through? Do they make a space where the electricity can't flow, or do they make electricity reverse in direction? Hmm.

Have a discussion and pause the video.

Restart when you are ready.

The answer here is that they make a space.

Remember I said that it opened the circuit up, didn't it? It would break the circuit.

There's certainly no barrier that's introduced here and that they don't make the electricity reverse direction.

So here's your very first task, understanding switches.

Number one, work in a group to model how a switch works.

You'll need two people to be the switch in this case and one person to be a cell and another one to be a bulb.

Everyone else will be the wires.

You've all got to stand in a circle and hold hands to make a complete circuit.

With the switch people standing next to each other, I wonder if the bulb will light up? How could you model the switch opening up and would the bulb stay lit up and why? Part two of this task is to work in a group to build a circuit with a switch.

There's two sections to number two.

A, build a simple circuit with one cell or battery, two wires and one device.

This could be a bulb, a buzzer, or a motor.

You need some way of knowing that your circuit is working.

The best way to do that is to add something that makes noise, moves or lights up.

B here says, use some extra wires and add a switch to the circuit.

Use it to turn the device on and off.

Then you can really investigate to see how the switch will work.

Well get building your circuits and restart the video when you are ready.

Hopefully you've had a good chance to work as part of a big group there, making a chain of people to show how a bulb and a cell will work.

These are some examples of maybe something that you thought or maybe something that you discussed while you were doing it.

We thought the bulb would light up when we all held hands.

Hmm, okay, so holding hands together, you can then make your pretend bulb light up.

We modelled the switch opening when the two people who are part of the switch let go of each other's hands.

This would've made the light go off because the circuit was incomplete and then electricity couldn't flow through it.

Yeah, that's right.

Electricity can't flow around a circuit if there's a break in it.

Now, here is the second task.

You had to work in a group and build a circuit with a switch.

Now your circuit might have looked something like this.

There's a switch there with a crocodile clips.

Everything's connected up in a circuit, so we know it works and then the bulb is able to come on.

I wonder if you turn that switch around, what would happen or did you check whether the motor or buzzer would turn off if you used the switch as well? Whatever you did, I'm sure you were able to get something working.

Let's dive into the next part of our lesson now, types and uses of switches.

Now, switches are used to control the circuits in many electrical appliances that we use every day.

There are lots of different types of switches as well.

Oh yeah, we saw lots of different types of them before, didn't we? The simplest type of switch is called a basic switch.

Here is a drawing of one.

You can see there's a connector at either end.

There are contact points and there's also a lever.

It's very similar to a lever that I've got here that I can use in electrical circuits.

There's the lever that goes left and right like that.

There are the contact points at either side and there are even these little parts here that you can unscrew to add your connectors.

It looks a little bit like this just underneath.

Now, when the switch joins together for these two contact points, it creates the circuit.

So then the electricity is able to pass through and then out the other side, isn't it? You can see if I turn my switch over, there are the different contact points and you can see the break.

So if I have a wire going into the top parts here, it would only flow to this part in the circuit and then the switch allows it to continue to the other side and continue out the other side.

This switch is very useful because you can control two different circuits at once.

They can both be off or one can be on or the other one can be on.

It's up to how you use it.

Now the movable lever here has a fixed contact point as well, and there are connectors to join underneath in an electrical circuit.

The lever is pushed down like you saw in my example, to make the complete circuit.

That allows the electricity to flow.

Toggle switches have a toggle on them, which keeps the switch in one position, on or off.

You may have seen these in light switches around your school or home.

In the off position, there's a little gap in the circuit.

It's incomplete and electricity can't flow.

A little bit like you saw on the backside of my switch I showed you.

Alex says, "I've got a toggle switch to control the light in my room." There's a toggle light switch, you can see one side is off and the other side is on.

I can clearly see that there's a light bulb symbol there, so we know which end it needs to be.

Push button switches have a button that is pressed and released, and I've got an example of a push button switch just here, it's a little bit small, so hopefully you can see it on my camera as well.

You can see the little red button on the top.

When you push that, it goes downwards and it causes the connection to be complete.

There will be a wire connected to either side there to complete the circuit.

In the drawing of the push button switch, you can see, you can see the button is pushed down and that connects things up.

Most of them have got a little spring inside that makes sure that the button will spring back up to its position after being pressed.

So it's a one use button.

Once it springs back up, it's ready to be used again.

Sofia says that her games console has got a push button switch.

Oh yeah, of course.

I can see one there.

A games console is there with a push button switch.

I wonder what that controls.

I don't think it turns it on.

That's a symbol on the other side.

Maybe that button is there to connect something else to it instead, once you push it, you don't want it turning off again straight away afterwards.

Slide switches are operated by moving a slider from one position to another.

Now there's two connectors on that drawing there, and the slider on the top can move backwards and forwards.

Sometimes it is designed so that the slider will ping back to position.

Other times the slider will stay in its place.

They're often found on appliances where you can choose different modes.

Oh, like in the washing machine we saw in the kitchen earlier.

The clock radio says Alex in his kitchen has got a slide switch.

Oh yes, I can see it there.

There's some slide switches to turn it on or off to put it on auto or to turn it into low or high mode.

Lots of different settings there with those sliders.

Reed switches are made from two thin metal strips inside a glass tube.

I can see the glass tube there in that drawing.

There's two connectors either end and then there's two metal strips as well.

Now, when a magnetic field is applied, the strips or reeds will touch and join together.

They'll then complete a loop.

When the magnetic field is removed, the reeds separate and the circuit is incomplete.

Reed switches are often used in security systems such as those in doors and windows.

So somebody opens the door or window and you weren't aware of it, it will tell you.

Next time you go to a shop, sometimes local shops on high streets have got special buzzers or bells that go off when the door is open.

That helps the shopkeeper know that someone else is in the shop.

So let's stop and think here.

Fill in the missing word.

Switches are used to control many electrical what? We use them every day like televisions, toasters, and mobile phones.

The word here is appliances.

Switches are used to control many electrical appliances we use every day, like televisions, toasters, and mobile phones.

Let's stop and think again.

Which of these are types of switches? Is it A, a toggle, B, a leapfrog, C, a table, or D, a slide.

Have a discussion and restart the video when you are able.

Okay, let's have a look at the answers.

Types of switches is A, a toggle or D, a slide.

There's a toggle switch and a slide switch.

I wonder if there were any other types of switch that you can remember as well, but I certainly don't remember a table switch or a leapfrog switch.

One of them sounds quite fun.

It's time for the final task of our lesson.

You are going to work as an electrical engineer here, so you need to design and build a switch to control a circuit and turn a device on and off.

The switch should be connected to the rest of the circuit by crocodile clips and stay in the position you choose without you holding it.

Good point, it needs to work by itself, doesn't it? Without you standing there the whole time.

Good luck with your task.

Restart the video when you are complete.

Okay, now you had to design your own switch that could be used to control a circuit.

So here's an example from Alex.

He says, I made my switch from a paper clip and two split pins.

I pushed through a rectangle of card.

Hmm, I wonder how it works? So for the view from the top of the switch there, there's a paperclip and there's joining onto a split pin.

Here's a view of the underside of the switch.

Little bit like I showed you in that switch earlier, there is the cardboard.

There's a wire to test the rest of the circuit as well, and there's the bottom end of the two split pins.

Remember, the pin goes into the cardboard and then splits like that, doesn't it? So when the paperclip is only touching one split pin, the circuit is open and the bulb doesn't light.

But when the paperclip is touching both split pins, the circuit is closed and electricity can flow and the bulb will then light up.

Fantastic, yes, you can use a paper clip and a split pin to make your own electrical circuits.

I wonder what you would choose to turn on and off? It's very similar to the switch that I showed you here.

Can you see the metal contacts on the other side there? Imagine that there's a paper paperclip attached to one end and that's swinging down to touch the other end.

That's effectively the same kind of design as Alex did.

So let's summarise our lesson.

Switches are used to control circuits.

Switches can break a circuit by making a space between components where the electricity cannot flow.

Switches are used to turn bulbs, buzzers and motors on and off, and different types of switches are used to control many electrical appliances that we use every day.

Hopefully this lesson has helped you to think of some different ways that you could invent a switch that's going to help you in your life.

I know a long time ago, televisions couldn't be controlled with a remote from the sofa or from the bed.

That meant that electricians could come up with an idea.

They created a circuit that would create a switch next to the bed or the sofa so that the person sitting or lying there would be able to turn it off without having to get up again.

It's a little bit lazy, but it was a really good idea and maybe that even helped people to come up with a first idea for the remote control.

Whatever ideas you've got from this lesson, I hope it's been a good one.

I'd be Mr. Wilshire, thank you very much for listening.