Lesson video

Hello, my name's Mrs. Finlay.

And in today's lesson, we're going to be looking at systems within design.

We're going to look at open and closed loop systems, but before we start, make sure you're somewhere quiet where you can hear my voice and you have with you some paper and a pen for today's lesson.

So make sure you've got with you your paper and pen and you're ready to start.

Let's look at what we're doing today.

Well, you've probably already done your intro quiz.

We're then going to recap on input, process and output.

Then we're going to move on and I'm going to teach you about a closed and open loop system.

And then you're going to have a go at designing your own or drawing your own.

And then as always, there's an exit quiz at the end of the lesson.

Keywords.

The first keyword today is closed system.

Now, this is where a circuit has to make a decision.

So it will give feedback.

And we're going to be looking at those in a minute.

So closed system.

Our second keyword is sensor.

And you might've heard of this already but this is a component that monitors change in a circuit.

And it might do that through changing light levels or temperature or pressure.

So closed system and sensor.

And that's our keywords for today.

Input, process and output.

Now, this is a bit of a revision from what you've done previously.

So let's look at those three terms, input, process, and output.

I'm going to show you three images now in that order.

Can you tell me what the system is? Let's have a look together.

Okay, I think you've got that really quickly.

Let's look together.

So let's look at what happened at the input stage.

So solar panels collect UV light.

Then that is processed in what we call an inverter.

And can you tell me what the output is? That's right.

Electricity is created, and in this case it's used in a light.

Fantastic.

Let's do one more just to make sure that you've got the process.

Okay, so this time, what do you think is happening? What sort of system? Okay, great.

So can you tell me what's happening in the input at the start? What's happening in the input section? Good, someone's putting heating on.

So it's switched on, it's controlled.

What happens during the process? Yeah, the boiler starts.

And then finally, the output is the radiators get hot.

And this is called a system.

In this case, it's a heating system.

Now, the input, that's where everything starts.

So that is triggered.

The heating is switched on.

Now, this might be on a timer or someone could manually do it.

That then makes the boiler start and it says, ooh, someone wants to switch me on.

Right, okay.

I know what I've got to do.

And then the output for that, the thing that happens as a consequence of putting the heating on start with is that the radiators get hot.

And it's really important that you remember this system because we're going to be using this in today's lesson.

Feedback in a system.

We are going to look at closed loop system.

Now, these closed loop systems react to change and they give feedback and they do that by making decisions.

So let's have a look together at our first system now.

So the heating timer in your house is programmed to come on between seven o'clock and half past seven.

Okay, I've got a question for you.

It's 6:59, is heating on? No, it's not.

Okay, another question.

It's 7:10, is the heating on? Yes, you've just become a feedback system.

You're making decisions.

Let's take that system a little bit further into our closed loop system.

So we know that heating in the home is coming on between 7:00 and 7:30.

So let's see how that will work, how the automated system would actually work.

So the system is waiting for seven o'clock to switch a heating on and it's going to keep checking until it's seven o'clock.

So the first question that your system is going to ask is, is it seven o'clock? Now, if it's not seven o'clock, what is the system going to keep doing? Yeah, it's going to keep checking.

Is it seven o'clock? No, not yet.

Is it seven o'clock? No, not yet.

So we're going to put those arrows all the way back to no and then back to the beginning.

Now, it's very interesting that we have got the question in this shape, okay? And all our questions will go into that shape.

So is the heating on? Is it seven o'clock? No? Asking the question again.

Now, if it's yes, what do you think is going to happen? That's right.

Our heating is going to be turned on.

I would like you to get your pen and paper.

Pause the video and write this piece down for me, please.

Okay, well, hopefully you've got that down.

So heating switches on between 7:00 and 7:30.

The system asks, is it seven o'clock? No? Keep checking.

If it's yes, the heating's turned on.

So if our heating's on, what's our next question going to be? Look at that box at the start.

So our heating's on between 7:00 and 7:30.

So once the heating's on, what is the heating going to be asking? Let's have a look.

Is it 7:30 yet? Absolutely.

Now, if it's not 7:30, our heating's staying on, but if it is 7:30, what happens to the heating system? That's right.

It's going to be switched off.

Okay, let's look at that together 'cause it's quite a lot.

Heating goes on between 7:00 and seven 7:30.

That's the instructions.

Your system's going to keep asking, is it 7:30? No, keep checking.

If it is, we're moving on and the heating's switched on.

Once the heating switched on, the system is going to keep asking itself, is it 7:30 yet? If it's not 7:30, it will keep the heating on.

If it is, it will switch a heating off.

So you see how this closed loop system is constantly giving feedback, making decisions.

I would like you to pause this video and write the last piece of this system in.

Okay, time to have a bit of a recap.

So a closed loop system is a system that makes decisions, okay? Gives feedback and makes decisions.

An open loop system is a system that doesn't make decisions.

So I haven't introduced you to open loop systems yet, but they don't make systems. So they're literally put something on, switch it off.

Okay, so boiling a kettle, open or closed loop system? What do you think? I'm going to read you what a closed loop system is and an open loop system.

Closed loop system is a system that makes decisions.

Does that kettle have to make a decision? An open loop system is a system that doesn't make a decision.

So do you think boiling a kettle is an open or closed loop system? Okay, I'm going to tell you the answer.

Makes decision.

Yes, it's a closed loop system because it has a sensor in there that will switch the kettle off when it reaches the correct temperature and the water is boiled.

In this instance with this kettle, it's a closed loop system.

I think you've done really well.

Let's do another one.

So just a reminder, closed loop system is a system that makes decisions.

Open loop sys, blah.

Open loop system doesn't make decisions.

So switching a light on to read a book.

Is that open or closed loop, do you think? Closed loop systems make a decision.

Open loop systems don't make a decision.

What do you think? Three, two, one, tell me.

Yeah, it's an open system 'cause you're literally putting that lamp on and switching that lamp off.

Okay, I'm going to ask you two more but in a slightly different style.

So is switching on the radio to listen to music a closed, make a decision, or open system? What do you think, closed or open? Switching the radio on to listen to it.

What do you think? Three, two, one.

Yeah, it's an open system 'cause you're just literally putting that radio on or switching that radio off.

I'm going to give you one more.

You're doing so well.

Okay, are street lights in a road, are lights in the road a closed, they're making a decision, or open system? What do you think? Street lights in the road.

Let's have a look together.

I'm going to really rush you on this one.

Yeah, it's a closed system.

Now, what component do you think would be used? Now, if you're saying something that senses the light, you are correct.

Amazing.

You could also use a timer.

So it might be that they come on at seven o'clock or they might use something where they use something like a light dependent resistor where they will sense when it gets dark and the lights will come on.

Great knowledge.

Well done.

So let's go back to our example of our street lights.

A closed loop system is a system that makes decisions.

So what are the two ways we can make decisions on our street lights? We talked about that light dependent resistor, didn't we? So let's have a look.

We've got a timer, say, lights on at five o'clock, for example.

Or the street lights could be activated by a light sensor.

And that's where we had our light dependent resistor that we've talked about previously.

So I'm now going to get you to have a go at creating your own systems. So let's think about those street lights.

It's up to you how you want to do this.

I'm going to start you.

And you might want to pause the video and have a go at doing the whole thing.

Or you might like to do this alongside me.

And that's fine.

So first thing is going to be, is it dark? Now, this is the point where some of you might want to pause the video and have a go at doing the whole decision-making, the whole system.

And that's fantastic.

And that'd be brilliant if you could do that.

But if you're not quite so confident, then let's do it together and we'll see how far we get.

Okay, so is it dark? If it's not dark, what is our system going to do? That's right.

It's going to keep the light off and it's going to keep asking if it's dark.

So on that, is it dark, there's obviously going to be our light dependent resistor that acting as a sensor.

Pause the video and copy this first section down.

Okay, so if it is dark enough, what's going to happen? That's right.

The lights are going to come on.

And that's our system.

Lovely and simple system there for you to have a look at.

If you haven't copied that down, have a go now.

We're now going to look at the kettle and we're going to do a similar thing.

We're going to write the system out.

Now, as before, you might decide that you want to have a go at doing this yourself, or you might like to do the work alongside me, and that's fine.

So let's look at the challenge.

Create your own closed system for this kettle, when it falls at 100 degrees C.

So now's the time to pause the video if you want to have a go at drawing this out yourself.

And if not, let's have a go at doing this together.

Okay, so our kettle is going to be switched on.

And then there's going to be a question.

So pause the video and have a think, what question might it be? I wonder if you got that right.

Okay, so question is going to be is the water 100 degrees? If it is, what do you think the kettle would do? If the water's hot enough, what will the kettle automatically do? That's right.

It's going to switch off.

Fantastic.

Now's the time to pause the video and write this part of the system on your paper.

Okay, so well done.

If we know what's going to happen if the water is hot enough, what happens if the water isn't hot enough? So is the water 100 degrees C? No.

Yeah, that's right.

The kettle is going to keep heating that water.

Now, what have I not put in that system that needs to go in there for that to make sense? That's right.

The arrow.

So that arrow's what's really important.

You need to keep that concentration up all the way to the end.

So is water 100 degrees? No.

Keep heating.

But because we've got a closed loop system, we're going to keep checking, getting that feedback.

So keep heating.

Is the water 100 degrees? No.

Keep heating.

Is it 100 degrees? Yes.

Switch it off.

Okay, I'm really pleased.

You've done really well.

Let's get you to write those down if you haven't written it all down.

So pause the video now if you've not written it all down.

And if you have, let's move on and test your knowledge a little bit.

Okay, so I've put the pause on.

What do closed loop systems do? Now, there is definitely more than one here.

So let's have a look.

Control systems, give feedback, make decisions, give no feedback.

So a closed loop system.

If you want to pause the video, that's okay.

What do you think they do? Let's have a little look together.

I'm going to get rid of the wrong answers.

Okay, so three things that they do.

They control systems. So controlling that that water isn't going to boil over.

We know that at 100 degrees, that switch is going off.

They give feedback.

Is it seven o'clock yet? No.

Is it seven o'clock yet? No.

Is it seven o'clock yet? Yes.

And they make decisions.

I'm going to switch that off.

I'm going to switch this on.

This is the right temperature.

So closed loop systems control systems, they give feedback and they make decisions.

So the last thing I wanted to look at was the advantages and disadvantages of systems in design.

Now, let's think about that.

Systems in design products are meant to make our lives easier because they make decisions for us and they automate things around us.

But obviously sometimes that isn't a good thing.

Let's have a think about how systems and the products that are designed around us can make our lives better.

Can you think of some examples? Let's have a look together.

Safety for families.

And I was thinking about smoke alarms with this, actually.

And the fact that there's a sensor on them.

And when that sensor senses a smoke, it makes a noise.

And that's obviously an advantage for us, but there are lots of other ways that we can have safety for families too.

And I'm sure you might've come up with a few.

Let's look at another one.

Saves us energy.

So making sure that the kettle switches off when the water is hot and it doesn't over boil is a great example of that.

Reacting to temperature changes.

So the heating in my home, if the house is warm enough, that actually will switch itself off.

So not only is it saving us energy but essentially it's saving me money as well.

So that's the third one I've got is saving us money.

And the last one I've come up with, efficient use of time.

So you don't have to be doing something or watching something, especially with cooking and things.

You can go away.

And you know that after a certain amount of time, the oven might switch off.

Really good example on that is if I was making a cake maybe.

Put the timer on.

When the timer finishes, it will switch the oven off for me.

Okay, so I wanted you just realise at the end of this lesson, that once we have all these things available to us, there are advantages and disadvantages to them and we must be aware of those as designers.

Well done today.

You've done really well of really tricky topic, closed loop systems. And I think you've done some fab stuff.

I will see you again soon.