Hello and welcome to today's lesson.

My name is Mrs. Mehrin and I am so excited to be learning all about variables in electric circuits, and we are going to be doing some planning today.

Welcome to today's lesson from the unit Changing circuits.

Now, your lesson outcome for today is: I can plan to investigate variables that may affect the brightness of a bulb in an electric circuit.

Now, I know that learning can sometimes be a little bit challenging, but that's okay, because we are going to work really hard together and we are going to do some fantastic new learning.

Now, you have got four keywords today.

I don't want you to worry about writing these down, because I am going to be going through these words throughout today's lesson.

However, if you find that it does help you to have these written down, you can pause the video here and you can do that now.

Off you go.

Fantastic, well done.

And here are all of the definitions for those four keywords.

Again, I am going to be referring to these throughout today's lesson, so you don't have to write them down.

However, if you feel that it does help you, you can pause the video here.

Off you go.

Fantastic, well done.

Now, today's lesson is split into two parts.

We have got variables in a circuit and investigating how variables affect bulb brightness.

Let's begin with the first part, variables in a circuit.

Now, Alex and Laura here have been building circuits and they have made a sign for their classroom which has a light bulb on each corner.

So this is the sign that they've made, Welcome to Class 6, and they have their light bulbs there on each of the corners.

Now, Alex and Laura want the light bulbs on the sign to shine brighter.

Now, they know that they can make a bulb brighter by increasing the voltage of the cells or the batteries in the circuit.

And Alex asks, "How else could we make the bulbs brighter?" Now, scientists carry out investigations, changing variables to learn about circuits.

Now, before we move on, I want you to just have a little think about Alex's question here and how else we could make those bulbs brighter.

I'll give you five seconds to think about your answer and then we will go through it together.

Off you go.

Fantastic, well done.

So one thing they could do is to change the bulbs themselves and go for a light bulb with higher watts.

Now, Alex and Laura have learned about variables in investigations, and Laura says, "When you do a fair test investigation, you should only change one variable each time." So this also means that you should control all but one variable each time.

So controlling that variable means that you are not changing it, you're keeping it the same.

So, only one of those variables should be changed at a time.

And now this allows you to look at the effects of changing just one particular variable on the results, so you can really see how changing that variable has affected, in this case, the circuit that they're creating.

If you go and change two variables at a time, you won't know which of those variables has actually had the effect that you were looking for.

So just choosing one at a time is the best way to do it.

And the children, they're not sure what the variables are in investigations with circuits.

Now, I want you to think, do you know what the variables are when you are looking at investigations with circuits? I'll give you five seconds to think about your answer and then we'll go through it together.

Off you go.

Fantastic, well done.

So variables are things that you can change in an investigation.

So let's look at this circuit here.

What can we change about it? Again, I'll give you five seconds and then I'll give you some answers and perhaps you will have thought of the same things that I did.

So off you go.

Fantastic, well done.

So, some of the things that Laura said is that you could change the number of cells.

Alex said that you can change the positions of where you put those components in the circuit.

You could add other components to the circuit.

And all of these things are things that you could change, and these are the variables.

Now, is there anything else that you thought of when I asked you this question? So you may have thought you're going to start adding things like motors.

So these are the other components to the circuit.

You may change the brightness of the bulb.

So you may go for different bulbs with different watts.

You may decide that you're going to use more than one cell or you're going to start using lots of batteries or different voltage of batteries.

So there's so many variables that you could change when you come to do this experiment.

Now, I want you to think about this question here.

It says, what is the name of things which you can change in an investigation? Is it A, changeables, B, variables, or C, flexibles? So think about what we've learnt together so far.

I'll give you five seconds to think about your answer.

Off you go.

Fabulous, well done.

The answer is B, variables.

Now, how many variables should you control, sorry, how many variables should you control in an investigation? Should you just be controlling the one, should you be controlling all of them apart from one, can you just control as many as you want or as few as you want, or two variables should be controlled in an investigation? So again, I'll give you five seconds to think about your answer and then we'll come back and we will discuss it.

Off you go.

Fantastic, well done.

So the answer is B, all but one, because you really want to see which of those variables that you're changing are actually having an effect on the circuit.

So here is Task A.

I want you to identify the variables in this circuit.

And now, to help you, I want you think about all the different things that you could change.

So have a really good look at this picture.

What components can you see and what could change? Okay, I'd like you to pause the video here and I'd like you to write down all the variables in this circuit and then come back once you are ready.

Okay, off you go.

Fantastic, well done.

So, you may have thought of these variables.

So the motor, the bulb, the cell, the switch, the positions of those components, the number of cells, and the batteries as well.

So you may have thought of all of those, you may have thought of some of those.

Well done.

Now we are on to the second part of our learning today, which is investigating how variables affect bulb brightness.

Now, there are different variables that can be changed in a simple electrical circuit.

So Laura says, "Changing the position of the bulb in the circuit." Alex says, "The number of cells.

Adding other components to the circuit." And we've already discussed some of the other things that we could change as well.

So for example, the bulb, maybe choosing bulbs with a higher watt so that it's going to be brighter.

Adding more powerful batteries, so batteries with a higher voltage.

There's lots of different variables that we could change.

Now, changing any of the variables in the circuit could affect the brightness of a bulb, and that's what they are wanting to test out.

So Laura says, "I would like to change the number of cells in my circuit to make the bulbs brighter," but Alex says, "I've just checked, and we only have two cells left! So we will have to change a different variable to see if it affects bulb brightness." Now, the children want to find out which of the other variables actually do affect the brightness of the bulb.

So what could their scientific question be? I'll give you five seconds to think about your answer and then come back once you are ready.

Off you go.

Fantastic.

So Alex says, "Which variables affect the brightness of the bulb in a circuit?" So that's a great question.

Now, I want you to think carefully about how they're going to investigate this.

So again, I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, they're going to start off by creating a simple circuit in order to be able to test this.

So Laura says, "We'll start with this simple circuit, then we'll change it to try to answer the question." And Alex says, "We will add a switch into the circuit and also change the position of the bulb." Now, do you have any advice for Laura and Alex when they come to do this experiment? I'll give you five seconds to think about your answer.

Off you go.

Great, well done.

So you might have noticed that Alex has got some different ideas about what they're going to do.

Some of the advice might be to remember to only change one variable at a time.

So just like with other types of investigation, when we explore circuits we should only change one variable at a time.

So Andeep says, "Don't add another component and change the position of the bulb at the same time.

You need to change each one separately, otherwise you won't know which one affects the brightness of the bulb." So let's do a quick check-in of your learning so far.

And the question says, which of these could affect the brightness of a bulb in a circuit? Is it A, connecting the bulb the other way round, B, adding other components to the circuit, or C, decreasing the voltage? So I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So the answers are B and C, adding other components to the circuit and decreasing the voltage.

Now, I want you to have a look at this question here.

It says, which variable has been changed in the second circuit? So have a look at the first circuit and then have a look at the second one.

What has been changed here in the second circuit compared to the first circuit? Is it the number of components, is it the voltage, or is it the position of those components? Okay, I'll give you five seconds to think about your answer.

When you are ready, come back.

Off you go.

Fantastic.

The answer is the number of components.

So the switch has been removed in the second circuit and everything else is the same, even though the diagram is just drawn at a different angle.

So the components haven't actually moved.

Now, here is Task B.

I want you to plan an investigation to answer the inquiry question, which variables affect the brightness of the bulb in a circuit.

So, I want you to observe what happens when you change these variables, so when you're changing the number of components, the position of the components as well.

And is there anything else that you can change? So we've discussed some of those already in today's lesson.

So what are you going to do and what are the circuits that you're going to build if there's something else that you could change as well? So I'll give you some time now.

I want you to pause the video here and I want you to have a go at this.

Off you go.

Fantastic, well done.

So here we have an example of what it might.

So here, this is the second part of your task for today, and it's to draw a table in which you're going to record your planned circuits and findings, like the one that's been started over here.

So you've got your basic circuit with one cell and one bulb, and you are going to write about the bulb brightness here.

Then we've got the number of bulbs.

So in the second one, the number of bulbs has changed.

You've got one cell, but now you've got two bulbs.

So again, only changing that one variable at a time.

So in this instance, it's the number of bulbs.

And then you're gonna test whether or not the bulb brightness has increased.

And then you are going to continue by changing just one variable at a time until you get the result that you are looking for.

So again, I'd like you to pause the video here and I'd like you to have a go at doing this.

Off you go.

Fantastic, well done.

So, here we've got Laura and Alex's.

And number one, it says to build a second with a cell, a bulb in a bulb holder, and connecting wires.

Then they put a cardboard tube over the bulb to block out light from the room.

They placed a light sensor at the top of the tube to measure the brightness of the original bulb.

They changed one variable in the circuit, example, adding a bulb and repeating steps two and three.

And then continue changing variables one at a time until they've tested each variable.

So here is the first part of their table.

They've got the basic circuit, they've got two cells and they've got one bulb here.

So very, very simple, very basic.

The second one, the number of bulbs has changed.

So they've got the two cells like they did last time, but they've also got two bulbs this time as well.

Now, the second part of the table is the position of that bulb.

So they've decided to change the position of the bulb.

In the first one they've put the bulb before the switch.

They've got two cells, one bulb, and one switch.

And in the second one, they've changed the position of the bulb again, but they've put it after the switch to see whether or not that has any impact on it.

It's got two cells, one bulb, and one switch.

Now here is the summary of your learning today.

A variable is any one thing in an investigation, including those involving circuits, which could be changed.

Changing the position of the bulb in the circuit may affect how brightly it shines, and adding other components to the circuit may affect the brightness of the bulb.

Well done, I am so proud of your learning today.

You've worked incredibly hard.

You've thought really carefully about your planning and how many variables you're changing, which is just one at a time, and the variables that you are going to change, and I am so proud of your hard work today, so well done.