Lesson video

Hello, my name's Mrs. Taylor, and thank you for joining me today for our lesson.

Our lesson today is Systems Approach to Design, and this is part of the unit Systems Approach to Design: Sustainable Futures.

The outcome.

I can identify the inputs, processes, and outputs in a control system.

There are four key words in today's lesson.

Context, which is the situation within which something exists or happens.

Design brief, a statement that explains what you are going to design and manufacture.

A variable, which is something that can change.

And feedback, which is a signal that is sent back in a loop, depending upon a condition.

There are two parts to the lesson: control systems and feedback.

Let's start with control systems. A context is the situation within which something exists or happens.

This is the starting point in the iterative design process.

The context for this unit is: sustainable futures.

We can explore the context and identify potential design opportunities or problems to solve.

The United Nations have identified 17 goals for a sustainable world.

They include: no poverty, no hunger, good health and wellbeing, quality education, and clean water and sanitation.

Here we have a check for understanding.

What is the starting point for investigating, analysing, and identifying design opportunities? Is it a, an idea; b, a problem; c, a design brief; or d, a context? Pause the video and have a go.

Wonderful.

Let's check.

That's right, it's a context.

Well done.

We are going to focus on no hunger and good health and wellbeing.

Izzy investigated this further and identified a design opportunity with homegrown produce using a greenhouse.

Here is Izzy's design brief: I'm going to design and make a control system to manage a greenhouse.

The control system will monitor the conditions and ensure the plants have the optimal environment to grow and thrive.

A control system is where a computer or microprocessor is used to respond to inputs and control outputs for a specific purpose.

This system's approach is useful when designing a control system.

We can see here the blocks input, process, and output.

We are going to use a micro:bit, which is a microcontroller.

This is what it looks like from the front.

Button A and B are inputs.

They can be used individually or together.

Additional offboard input and output components can be connected via the five pins.

The first row of LEDs can be used as inputs.

These can sense light levels.

The 25 LEDs are outputs which can be used to display patterns or words.

These can be programmed individually.

Here we have a check for understanding.

The LEDs on the front of a micro:bit are used to: a, sense light; b, display patterns; c, sense movement; or d, display words.

Pause the video and have a go.

Wonderful.

Let's check.

That's right, it's a, b, and d.

They sense light, they can display patterns, and they can display words.

Well done.

This is the back of the micro:bit.

The microphone is an input component that can react to noise.

The micro:bit uses an onboard processor that receives inputs and controls outputs.

There is a temperature sensor here, too.

The speaker is an output component that can play sounds.

The accelerometer is an input component that senses forces.

Combined in the same chip, the compass is an input component that can identify magnetic north.

Here is a programme where the onboard temperature sensor is the input and the output is a graph displayed on the 25 LEDs.

The built-in temperature and light sensors can be controlled in a simulation by adjusting the sliders, as we can see here.

The code uses the output block plot bar graph.

The input block temperature is added and set up to 50 degrees Celsius.

This will display the output using the LEDs as a bar graph.

We can see this clearly in the zoomed-in section here.

Alternatively, we could use an if statement.

Here, if the temperature is above 30 degrees celsius, then the output connected to pin zero will be high, which means on.

In this example, it is an LED.

We can see in the zoomed-in section if the temperature is greater than 30, then digital pin zero will be high.

Else, digital pin zero will be low, which means off.

Here we have task A.

The first part is to open Tinkercad, and the second part is to open this exemplar programme from the gallery.

Part three: Simulate the programme.

Part four: Describe what happened, including identifying the input and output.

Part five: Change the input and the output to monitor the light levels and turn on the LEDs when dark.

Part six: Simulate the new programme.

And part seven: Describe what happened.

Pause the video and have a go.

Fantastic.

Let's have a look at some of the answers you may have come up with.

For part four, you may have said, "In this programme, button A is the input and the output is an arrow shape illuminated on the LEDs.

There is a wait after the LEDs have illuminated, and then they go off.

If I press button A again, the arrow appears again and then goes off." For part seven, in this programme, when the light levels are below 10, the LEDs in the shape of an arrow illuminate.

When the light levels are above 10, the LEDs do not illuminate.

This could be adapted to use an off-board output, such as a bulb or a series of LEDs.

Well done.

We now move to the second part of our lesson, feedback.

Before we can design a control system, we need to analyse the design brief to ensure the system meets the requirements.

Here we have Izzy's design brief: I'm going to design and make a control system to manage a greenhouse.

The control system will monitor and maintain the optimal conditions for the plants to grow and thrive.

Here we can see that she's going to design and make a control system to manage a greenhouse, monitor and maintain, to ensure the plants grow.

Here is a picture of a greenhouse.

In order for the plants to grow and thrive, what do they need? Pause the video and have a think, or talk to the person next to you.

Wonderful.

Izzy says, "I think the plants need light, water, and the correct temperature." Here we have a check for understanding.

Before designing a control system, you should: a, visit a greenhouse; b, analyse the design brief; or c, grow a plant from seed.

Pause the video and have a go.

Wonderful.

Let's check.

That's right, it's b.

Analyse the design brief.

Well done.

Our control system will need to monitor and control the different aspects within the greenhouse.

These aspects can change, anything that changes is called a variable.

Light, moisture in the soil, and temperature are all of variables because they can change.

Izzy explains why she wants to monitor these variables.

Plants need light to grow.

In the winter months, there might not be enough daylight.

The plants also need moisture, so the user will need to water the plants when the soil is dry.

Plants can wilt in the summer in a greenhouse as it becomes too hot.

If the temperature is too hot for the plants to thrive, we might want to open the window in the greenhouse.

And we can see this in the systems block approach to design.

For example, the input would be to measure the temperature, the process would be to check the temperature against the variable, and the output would be to open the window.

Here we can see a flowchart showing more detail than the block diagram.

It begins with start, and the first task is to measure the temperature.

Then there is a decision.

Is the temperature above 30 degrees Celsius? If no, the window is closed, and the flowchart starts again by measuring the temperature and asking the question, is the temperature above 30 degrees C? If the answer is yes, the instruction is to open the window.

A signal that is sent back in a loop, depending upon a condition, is called feedback.

In this example, we need to check the temperature and either open the window or close it using feedback.

A flowchart is a good way to show this.

Here we have a check for understanding: Feedback is a, an input signal; b, an output signal; c, a signal fed back in a loop; or d, a continuous process.

Pause the video and have a go.

Fantastic.

Let's check.

That's right, it's c, a signal fed back in a loop.

Well done.

Izzy has identified the inputs and the outputs she would like to include in her control system and planned this using a table.

Here we can see the first input is measure light levels, with the process check light levels against variable and the output to turn on or off a light.

The second input is measure temperature, with the process check temperature against variable and the output open or close the window.

The third input is measure moisture in the soil, with the process check moisture against variable and the output warning on or off to the user.

Here we have task B.

Analyse your design brief and identify the system requirements.

Part two: Analyse the greenhouse and identify which aspects need to be monitored.

Part three: Plan the inputs, processes, and outputs of your control system using a table.

Part four: Draw a flowchart to show two different inputs, the outputs, and include a variable.

Pause the video and have a go.

Wonderful.

Let's have a look at some of the answers you may have come up with.

Izzy analysed her design brief and identified that she's going to design and make a control system to manage a greenhouse, which will monitor and maintain conditions in order for the plants to grow.

For part two, she analysed the greenhouse.

She would like to monitor: moisture in the soil, light, temperature, and ventilation.

For part three, Izzy planned the inputs, processes, and outputs of her control system using a table.

She would like to measure the light levels with the process check light levels against variable and the output turn on or off a light.

She would also like to measure the temperature with the process check temperature against variable and the output open or close the window.

And the third input that she would like to use is to measure the moisture in the soil with the process check moisture against the variable and the output a warning would be on or off to the user.

For part four, here we can see Izzy's flowchart for the part of the system which is measuring temperature and either opening or closing a window.

The variable in this case is the temperature.

Here is another flowchart which Izzy created to test the moisture in the soil.

And here, the output would be a blue LED that she would use as an alert.

Again, there is a variable.

In this case, the moisture in the soil.

Well done.

Here we have a summary of our learning.

A context is the situation within which something exists or happens and is the starting point for an interactive design process.

After investigating the context, we then write a design brief, which is a statement that explains what you are going to design and manufacture.

Systems use inputs, processes, and outputs, and can also include variables and feedback.

Systems can be planned using flowcharts.

I'm so pleased you could join me today.

Thank you, and well done.