Lesson video

Hello, my name's Mrs. Taylor and I'm really pleased you can be here to join me for the lesson today.

The lesson is; Develop and modify code, and this is part of the Functional Prototypes Wearable Technology Unit.

The Outcome, I can develop and modify a system to meet the requirements of a design brief.

We have three key words, design brief, which is a statement that outlines the requirements of a product, iterate, which is the process of refining and improving a design, and justify, which is to explain why something is done.

There are two parts to the lesson.

The first is design brief, the second is develop a programmable system.

Let's begin with design brief.

The context in this unit is wearable technology.

The design brief is: To design a wearable system to keep children safe when walking to and from school in the dark.

Let's begin by analysing the design brief, we will use the 4 W's.

The 4 W's are; Who, What, Where, and Why.

To design a wearable system to keep children safe when travelling to and from school in the dark, Who is the children, What is the wearable system, the Where is travelling, and the Why is to do with being safe in the dark.

Here we have a check for understanding, which W's are useful when analysing a design brief? Is it A, What, B, Why, C, Whether, or D, How? Pause the video and have a go.

Wonderful, let's check.

That's right, it's A and B, What and Why, well done.

To refine the design brief, we consider each W and ask some questions.

Who, this is the children travelling to school.

What age child will you design your wearable device for? How do they travel to school? Does the child travel alone, with an adult or with other children? Sam and Izzy explain who they are going to design a wearable system for, and justify their decision.

Sam says, "My younger sister walks to school with our gran.

So I am going to design a wearable device for young children that walk to school with an adult." Izzy says, "I am going to design a wearable device for teenagers that cycle to school because I cycle to school." Here we have a check for understanding.

When making a design decision, it is important to also, A, justify it, B, state it, C, design it, or D, make it? Pause the video and have a go.

Great, let's check.

That's right, it's, A, justify it, well done.

To refine the design brief, we consider each W and ask some questions, so for What, which is the wearable system to keep children safe in the dark, we could ask the questions, Where can systems be worn? Or, How can children be kept safe in the dark? Sam and Izzy explain what they are going to design and justify their decision.

Sam says, "I'm going to design a wearable device for young children that lights up automatically, it could be attached to the child's coat or book bag." Izzy says, "I am going to design a wearable device that can be attached to the cyclist's bag or coat." Here we have Task A, Design Brief.

To design a wearable system to keep children safe when travelling to and from school in the dark.

Part 1 is to refine the design brief.

The success criteria are to use the 4 W's, and justify your design decisions.

Pause the video and have a go.

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

Sam and Izzy share their refined design briefs.

Sam says, "I am going to design a wearable device for young children that lights up automatically.

It could be attached to the child's coat or book bag.

It will be used when walking to and from school in the dark.

The light will make sure that other people can see the child, which is really important when crossing the busy road near our house." And Izzy says, "I am going to design a wearable device that can be attached to the cyclist's bag or coat.

This will make sure that the other road users can see the cyclist and make it quicker and easier to use than attaching more lights to the bike itself." Well done! We're now going to move to the second part of the lesson, Develop a programmable system.

We can now develop or iterate a programmable system to meet the requirements of the design brief.

Sam wants his device to light up automatically when it is in the dark and can justify this decision.

"Because my device is for young children, I think a switch or button to turn the device on and off would be fiddly, but also they might forget.

An automatic sensor would be better." Here we have a check for understanding, Which components resistance changes depending on light levels, is it, A and LED, B, a thermistor, or C, an LDR? Pause the video and have a go.

Great, let's check.

That's right, it's an LDR, a light-dependent resistor, well done! To plan his programmable system, Sam identifies the different stages of the system.

The Input is the LDR resistance changes depending on the light levels.

The Process is the micro:bit processes resistance and activates the output LEDs if dark, and the Output is LEDs emit light.

Sam has some design decisions to make about his system.

How will the light levels be sensed? Is this on or off board? Are the output LEDs on or off board? There are 25 built in LEDs on a micro:bit, the first row of which also sense light levels.

The advantages of using onboard inputs and outputs include; it is quicker and neater to create.

The disadvantage is that they are in fixed positions and the LEDs are limited to one colour.

Sam describes the function of this system he has designed previously.

In the programme, the if statement has two options: when the LDR is in the dark and pin 0 reads less than 60, the red LED connected to pin 1 will be on and the green LED will be off.

When the LDR is in the light and the pin 0 reads greater than 60, the green LED connected to pin 2 will be on and the red LED will be off.

To iterate this system, he wants to reduce the number of off board components.

How could he do this? Here we have a check for understanding.

What are the advantages of using onboard inputs and outputs, is it, A, quicker, B, slower C, untidy, or D, neater? Pause the video and have a go.

Great, let's check.

That's right, it's both A and D.

It is quicker, and neater, well done! Sam iterated the system to use the onboard light sensor and onboard LEDs.

He wrote the code so that if an off board output component was added to pin 1, it would also work.

Sam iterated his circuit and programme to meet the requirements of his design brief.

He explains, "I used a light sensor to sense the light levels as this will then be automatic.

I used the built-in LEDs and changed the pattern to make it appealing to young children." Sam explains and justifies his design decisions.

"I also changed the programme as I didn't want any LEDs on whilst it was light, but I wanted all of them on in the dark.

I added wait times to the programme so they flash on and off, which makes them much more noticeable in the dark." Here we have Task B, Part 1, Decide if you are going to use the on board or off board inputs and outputs.

Part 2 iterate your system to meet the design brief requirements, and Part 3, explain and justify your design decisions.

Pause the video and have a go.

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

Here is Izzy's developed system.

We can see that she has added six LEDs, three of which are connected to pin 1, and three are connected to pin 2.

She explains and justifies her design decisions.

"I changed the programme to start on a shake, this will be easy for the cyclist as they put their bag on.

I changed the colour of the LEDs and then programmed them to flash on and off, which will make the device more noticeable.

I changed the if statement to a repeat sequence unless button A is pressed.

When button A is pressed, the LEDs will be off and this is how the cyclist can turn off the device when they get to school." Well done! Here is a summary of our learning today.

It is important to refine the design brief before designing a programmable system.

This will focus your design and ensure it meets the requirements.

Programmable systems can be planned using the systems approach, input, process, and output.

Iterating designs using simulation software is quick and easy to do and does not involve expensive components.

Once a design has been developed, it is important to explain and justify your design decisions.

I'm really pleased you could join me today, thank you, and well done!.