Hello there, my name is Mrs. Dhami.

Thank you for joining me for your design and technology lesson today.

Now the big question for today is which materials fit into which material category, and how can those materials differ within the category, be that different working properties or physical properties, and why we might choose a particular material for a particular job.

So hard hats on.

Let's get cracking.

Our outcome for today is that we will be able to name specific examples of materials from each material category.

We have five key words today.

Our first two are physical properties and working properties.

I'll explain those when we get to the point in the slides.

Then we have naturally occurring, which means it comes from nature.

It's not made or altered by humans.

Manufactured, meaning produced by humans, often using machinery.

And lastly, synthetic, made through chemical processes.

We have two learning cycles for our lesson today.

The first one, we would categorise timbers, metals, and papers and boards.

And in our second learning cycle, we will categorised polymers and textiles.

So let's start off with categorising timbers, metals, papers, and boards.

On your screen, you can see loads and loads of different examples of materials.

Now, I've cut up all of these in my workshop and gathered a few from home.

So my question to you is, which categories of materials can you identify from this collection? Have a think, have a look, have a share with somebody in your class or with me, and come back to me when you found some categories.

So Andeep says, "I can identify lots of timbers within there." I wonder which categories you manage to find.

Material categories and specific materials are often chosen for their properties, depending on the specific use of the material.

We'll start with physical properties.

These are the characteristics of a material, such as appearance and features.

And a really easy example of a physical property is the colour of a material.

We then have working properties.

Now this is the way in which a material responds to an external force or certain environment.

We can also refer to it as mechanical properties, and a great example of this is how flexible a material is.

Let's get started with timbers.

So timbers can be categorised as hardwoods, softwoods, or manufactured boards.

So here's a bit of a zooming of some of the samples that I cut up.

Can you identify any of those categories within timbers from this collection? Pause the video, have a good think.

Come back to me when you've got an answer.

Hopefully you manage to find an example of each of those categories.

We'll go through these in the following slides.

Let's recap a little bit of knowledge about the difference between hardwood and softwood.

So let's start with softwoods.

They come from ever grown.

Ever grown? Evergreen trees.

Now they're the ones that have needles that stay on all years.

They always look quite green.

They grow quickly, making a loose grain, but this means it is cheap and sustainable.

Whereas hardwoods, they come from deciduous trees.

Now, those trees are the ones where the leaves change colour and they fall off, so it's just left with the branches in winter.

They grow really slowly, which means that the grain is close.

Now compare that diagram on the right of the hardwood in comparison to the grain on the softwood.

You'll see, with the hardwoods, those growth rings are much closer together, so they only grow a tiny bit every single year.

Now, this gives them a really amazing finish in comparison to a softwood.

But, obviously, because they take so much longer to grow, it makes them a lot more expensive.

Time for our first check-in.

which statements are true for a hardwood? A, close grain, B, takes longer to grow than softwood, C, grows quicker than a softwood, or D, comes from evergreen trees.

Have a little think.

Come back to me when you've got an answer.

Okay, well done If you manage to identify A and B.

They have close grains and they take a longer time to grow than softwood.

Well done if you got those right.

Let's start with softwoods in a bit more detail.

So softwoods are obviously naturally occurring.

Now, I'm sure you've probably all heard of pine.

Pine is the first picture, the top picture on the right-hand side.

It is lightweight and it's extremely easy to work with, and you'll often find that in roof joists and floorboards.

Now, in a complete contrast is cedar.

Now, cedar is also a softwood, but it has completely different properties to pine.

Cedar is weather resistant, and that's due to its natural oils, making it resistant to water and fungal growth.

Therefore, it is a brilliant wood to use outside for things like fences and sheds.

That's because, obviously, it's being exposed to all those different weather conditions.

Pine would not stand up so well outside.

Next up, we have hardwoods.

Just like softwoods, They are naturally-occurring.

Now, we'll start with oak.

Oak, as you may or may not know, is very durable, and it has a beautiful attractive grain when it's finished.

I love oak.

I really do.

Example products tend to be high-end furniture.

Now, in complete contrast is balsa.

If you were in my classroom now, I'd be throwing a big block of balsa right at you.

And you might think, "Oh, an awful teacher." Well, actually, the reason I would be doing it is because it is extremely lightweight.

It almost feels like styrofoam.

It's that light.

But the one thing that is confusing and people don't think of it as a hardwood, when actually it is, is because it is very soft, which means it can be scratched and indented just like styrofoam.

So lots of people think it cannot possibly be a hardwood because it is not hard, but actually it is.

It grows extremely slowly and has got a very, very close grain, and is often used for model making.

Next up, manufactured boards.

See that keyword, manufactured? Meaning human-made.

Manufactured boards are made from both soft and hardwoods.

First up is MDF.

Now, MDF is made from a load of wood dust and fibres mixed together with a load of glue, and then compressed into a flat sheet.

They're brilliant because it's very affordable in comparison to soft or hardwoods, however, does not have the same strength properties as a softwood or hardwood.

They're commonly used in the building and furniture trade.

Next up is plywood.

Now, plywood is made of really, really thin layers called veneers which are stuck together with the grains going alternate directions.

This therefore gives it loads and loads of strength.

Now, the grain on the two outside layers though always go in the same direction so that it does not warp.

Plywood is also used in the building and furniture industry and for parts that need better strength than MDF.

Quick check-in, match the picture to its label.

So on the left, we start with pine.

In the middle, we have oak.

And lastly, on the right, we have plywood.

Have a think.

Come back to me when you've got some answers.

Okay, hopefully for A, you managed to get pine, and that's going across to the picture on the right.

The middle picture B for oak, and the left hand side picture for plywood.

You can see those layers, can't you, in that plywood? Onto metals.

Now, metals occur naturally in ores which are mined.

They can be categorised into three main groups.

We have ferrous, non-ferrous, and alloys.

Have a little look at all the examples that I've got for my workshop at school.

I would like you to have a little look quite closely and see if you can identify any examples of each of these categories from this collection.

Pause the video, have a little look, come back to me when you have an answer, and then we'll look at them in more detail over the next few slides.

Ferrous metals is a mined metal containing iron.

Most are magnetic and rust apart from stainless steel and wrought iron.

We're gonna start with cast iron.

Now, if you look straight over to the example, I'm sure you recognise these from your workshops.

These are metal vices.

Now, cast iron is used to make those metal vices.

It has a very hard skin.

It's very brittle.

So if you actually got that and dropped it on the floor, and I do not suggest that you do that, it will quite often crack open because it is brittle.

It has a soft core.

It is also magnetic, and you can try that out at school with a magnet.

Example products include obviously vices, but also manhole covers.

And next one in complete contrast is stainless steel.

Now stainless steel is a ferrous metal, but it's also an alloy.

And I'll explain more about alloys in a couple of slides time.

Now, it's an alloy with chromium, magnesium, and nickel.

Now , stainless steel is corrosion resistant, hard, tough, magnetic, resist wear, but is also difficult to cut.

Great examples of this tend to be cutlery, sinks, and surgical equipment.

Obviously, you want all of those things to be corrosion resistant because they are going to come into contact with a lot of water and a lot of chemicals.

So stainless steel is perfect for that job.

Next up is non-ferrous.

Non-ferrous are mined metals which do not contain iron, and that's the main difference between ferrous and non-ferrous.

So non ferous do not contain iron.

They are not magnetic and they have a higher resistance to rust and corrosion.

So let's start off with aluminium.

Aluminium is great 'cause it's corrosion resistant.

It's malleable, excellent strength-to-weight ratio, but it also has a low melting point.

Now, this is great because often you'll find that drinks cans are made from aluminium.

Now, they're obviously full of liquid, so it's a heavy product, so you want it to have a really low weight to it, but you also want them to have a low melting point so that they can easily be melted down and recycled.

You can also though find aluminium in aircraft foil and engine parts.

Next up in contrast again is copper.

Just like aluminium, it is corrosion resistant and malleable, but it's also ductile with really good heat and electrical conductor properties.

So therefore it often gets used in things like electrical wire and printed circuit boards due to its really good electrical conducting properties.

You'll also notice it's quite a distinctive colour.

It's that bright red/brown colour.

Now, I use it a lot at my school with my jewellery club and we make some beautiful jewellery from copper, and we choose it because, A, of the colour, but B, also because it's malleable and ductile.

Let's take a closer look at alloys.

Alloys are manufactured by mixing metals or combining with other other elements to make them stronger, harder, lighter in weight, or better in some way.

So if we start off with brass, brass is made from copper and zinc.

Now notice the changing colour.

It's not that red/brown colour that we had before.

It's now changed from a more yellowy goldy type colour.

Now, properties of brass are, it is durable, it has good corrosion resistance, it casts well, and it polishes well.

Again, it's another one that I use at jewellery club because I love the colour of it, but it also polishes so beautifully for lovely pieces of jewellery.

It's also used in musical instruments, letter boxes, padlocks, plumbing fittings.

I have a padlock made from brass, which is used on my back gate.

And the reason I use it is because it's got good corrosion resistance.

In contrast, we have solder, which is also an alloy.

It's an alloy with lead and tin, but that's just one combination.

You can get all sorts of combinations of solder alloys.

Now solder is great because it has really good electrical conductivity and a low melting point.

Now, if you have done any electronics during your design and technology education, then you will have used solder to join your electrical components together.

And it's exactly what it says with the working properties.

It allows the electricity to flow through the components and through those joining points that you do, but it's great because it's got a low melting point, so all we need is a soldering iron.

Other examples are pipe work joint in plumbing.

As I said, I have a brass padlock on my back gate.

So padlocks are often used outside on gates or sheds.

What makes brass suitable for a padlock? A, electrical conductivity, B, malleable, C, corrosion resistance, and D, durable.

Come back to me when you've got an answer.

Fantastic.

Hopefully, you've identified C and D.

Brass is corrosion resistance, which is great for being outside, and it's also durable, which means it is long-lasting and can be used for many, many years outside.

Quick tip, remember you are relating the product to its use, and that's really important for questions later on too.

Onto paper and boards.

Now, paper and boards originate predominantly from timbers.

However, you will see an exception in a minute.

And they are manufactured into two main categories.

So we have paper, which is measured in grammes per square metre.

And then we have boards which are card and cardboards, and they tend to be measured in millimetres 'cause obviously they're a little bit thicker.

So I would like you to have a little look at the examples on the right hand side, see if you can identify any of those two different categories from those pictures.

And then we'll have a look at them in a bit more detail over the next few slides.

Come back to me so we can carry on once you've had a little go.

First up is paper.

Now, that is measured in weight, grammes per square metre.

That's because paper is exceptionally thin.

Now as we know, paper is flexible and lightweight.

As for physical properties, it's available in a range of colours and finishes.

And we find paper in newspapers, magazines, bus tickets, receipts, and toilet paper.

Next up is corrugated cardboard that is three millimetres thick, and the thickness increases.

You can get much, much thicker.

Now, basically, if you look at the picture on the right, you will see it has two layers of card with a fluted sheet in between.

Now this is commonly used for pizza boxes and packagings.

So if you order something off the internet, it is likely to come in a corrugated cardboard box.

Therefore, properties-wise, it needs to be strong, lightweight, and have good impact resistance.

Now the last one is foam board.

And this is a little bit of an exception because, yes, it has card either side, which therefore originates from timbers, but in the middle it is made from polystyrene, which obviously, as you know, is a polymer.

So it comes in thicknesses starting from five millimetres thick.

It's often used in modelling.

You might have used it to model some of your products within your design and technology education, and it's also used for point of sale displays where new products are often advertised in a shop window.

Therefore it is lightweight, making that a perfect property for a point of sale display, but it is also rigid.

Onto task A.

So we have a chart, as you can see, with four different products in.

What I'd like you to do is suggest a suitable material choice for each of those products.

But rather than just going out and giving us a straight guess, I'd like you first of all to about the product.

What working properties does it require? Then suggest a material category to then within that material category suggest a suitable material.

Good luck.

Have a good think.

Come back to me when you've got an answer.

Let's take a look at our answers.

So we'll start off with the fence panel.

It needs to be weather resistant, doesn't it? With all the rain, the snow, the ice, the wind, it's gonna face a lot, it needs to be weather resistant.

Suggesting material category could be a timber.

It doesn't have to be, but it could be.

Now, it'd be lovely to say hardwood here.

However, as we know, the price of hardwoods is very expensive.

So I'm gonna suggest softwood.

And the suitable material would be cedar because cedar has a high natural oil and rubber content, making it perfect for the job.

Next one is electrical wire.

Obviously, we want the working properties for it to have electrical conductivity.

So a great material category would be metals, non-ferrous, and I would suggest copper.

And if you've used any wires to join pieces of electronic components together, you might have noticed that the copper tends to be inside those insulated wires.

Next up is pizza box.

You would want that to be lightweight and impact resistance, sorry, have impact resistance.

Suggested material category would be paper and boards and suggested material would be corrugated cardboard.

Lastly, we have bus tickets.

Required working properties being that it will be nice and lightweight so they can have lots and lots of tickets on a reel.

You'd also want them to be really easily printed on as well.

Suggested material category would be paper and boards.

But because we want it so thin, it would definitely be paper.

Well done with all of your efforts.

The image on the right shows my teacher's table in my workshop.

So the image shows a school desk.

It is manufactured using a timber.

Part two, I would like you to identify the timber used.

Three, explain why this timber is suitable.

Four, name a material category which is mined.

So we're not looking at the picture now.

Part five, define and give an example of an alloy.

And then lastly, for part six, point of sale shop displays are often made to advertise and promote new products.

What is foam board and why is it a suitable choice for a point of sale display? Good luck.

Come back to me when you've got some cracking answers.

Let's take a look at our answers.

So my desk in my workshop is made from MDF with a polymer laminate on top.

That means that there's a polymer, a thin piece of polymer put on top of that MDF.

Part three, MDF is a manufactured board, meaning it is human made.

It's human made by compressing sawdust into sheet form.

This makes it cheap in comparison to a hard or softwood.

The polymer, however, provides a more durable surface for day-to-day use.

So if I spill my cup of coffee, I can easily wipe it up.

Part four, metals are the ones that are mined because metals appear in ores.

Number five was about alloys.

Alloys are manufactured, so human made, by mixing metals or combining with other elements to make them stronger, harder, lighter in weight, or better in some other way.

An example is solder, which is often used when joining electronic components.

And then part six, this was the point of sale display.

So foam board is lightweight polystyrene foam sandwiched between two pieces of thin card.

It is suitable for a point of sale display as it is lightweight, low cost in comparison to sheet polymers, and can easily be printed on.

Well done with all your hard work.

Onto learning cycle number two, we're going to now categorise polymers and textiles.

Polymers can be categorised as thermo or thermosetting.

And again, you can see some of the examples I have collected around my school and around my home.

So can you identify any examples of thermo or thermosetting from this collection? Have a little think, pause the video, come back to me when you've got some ideas, and then we'll go through some ideas over the next few slides.

Thermo polymers and thermo setting polymers can also be categorised as naturally occurring, comes from nature, not made or altered by humans, or synthetic, manufactured through chemical processes.

Within both of these two categories, some are biodegradable and others are not.

Polymers can often be identified through the number inside their recycling triangle.

And you can normally find this at the bottom of a product.

So for example, with a milk bottle, make sure the lid is nice and tight on it before you turn it upside down.

But on the bottom, you'll see imprinted into the plastic, so the same colour as the milk bottle, you will see a little triangle with the number two in the middle of that.

And that's because milk bottles are made from HDPE, which is in the category of number two for thermo polymers.

Thermo polymers melt on heating and can be reshaped.

So with first one is HDPE.

That stands for high-density polyethylene.

It's a synthetic polymer made from fossil fuels.

It's lightweight, resistant to chemicals, and has high impact resistance.

And you can normally find it in milk bottles, bottle lids, or wheelie bins, the recycling, the refuse wheelie bins.

Now, we melt them at school to make sheets of HDPE because it has a low melting temperature too.

Next up is PLA.

You may have heard of this one.

'cause if you've got a 3D printer in your school, it's very, very likely to use a PLA filament.

It's manufactured and it's often made from corn starch or sugars.

This is my favourite one.

It's biodegradable and has a really low melting point.

Again, that's why it's used in schools.

That's why it's used so well in 3D printers, because the 3D printers doesn't have to be heated to an extortionate temperature, but it is biodegradable.

Try and remember that fact.

Last one is shellac.

Now, you might have heard of this if you have ever had your nails done at a beauty place.

It's that now varnish that they put on, and then you put it under a UV lamp to set it.

Okay, it's a naturally-occurring polymer.

It's secreted by the lac bug.

Now, it's not.

Let's put it like this.

It's like a snail.

You know how a snail, if it rides along.

Rides along? If it moves along, it leaves a trail.

That's what the lac bug does.

Now, that is collected to make shellac.

Bet you didn't know if you've had that on your nails, that that's where it's from.

It's also used in timber varnishes.

Even though it's naturally-occurring, it does not easily degrade.

thermosetting polymers do not melt on heating.

They do burn if they're put at extremely high temperatures, but they don't melt, so you can't easily reshape them into something else.

This often makes them very difficult to recycle.

Our first one is urea-formaldehyde.

You've gotta have a go at saying that word.

What a word.

So it is a synthetic polymer from fossil fuels, it's heat resistance, and it's an electrical insulator, therefore it's great for plug sockets and light switches.

So your urea-formaldehyde is probably used in every room that you go into.

Next up is silicone.

Silicone is also a synthetic polymer from fossil fuels.

It has excellent heat resistance and is non-stick.

And you've probably seen a couple of examples of this.

So first of all, baking trays or cupcake cases that you can put into the oven, you obviously don't want them to melt on heating.

Therefore, silicone is one of those polymers that can actually go into the oven.

The other use of silicone is bathroom sealant.

So if you think about getting in the shower or in the bath, there's often this white kind of bit that joins the tiles to the bath or tiles to the shower tray.

That bit, that white bit that goes around is bathroom sealant, and that's normally made from silicone.

Three products, which one is made from a thermo polymer? A is a plug socket.

B is a cupcake case.

C are bottle tops.

Come back to me when you've got an answer.

Fantastic if you manage to get C.

C is the only product that we would want to melt with heating.

We definitely would not want the plug socket or the cupcake case to melt on heating.

Well done if you got that right.

Onto textiles.

Textiles can be categorised as natural fibres, naturally occurring from plants or animals.

And then synthetic fibres.

There's that word again.

Synthetic, meaning from a chemical process.

And synthetic fibres usually come from fossil fuels.

These can be mixed to create mixed or blended fibres too.

Have a little look at the examples.

Pause the video, see if you can identify any of them, and then we'll cover them on the following few slides.

Natural fibres are naturally-occurring, found in plants or animals.

Two examples, so first one, cotton from the cotton plant.

It is soft, biodegradable.

Breathable is one of the main properties that people want it for, and it's also comfortable.

It's often found embedding and T-shirts.

Next up is wool from sheep but also from other animals too.

It's soft, it's biodegradable, it's flexible, but it's also very insulating.

That's why sheep have it on them to keep them warm in the winter.

So you often find woollen products in things like scarves, hats, and blankets that are commonly used in the winter to keep us warm.

Next up are synthetic fibres.

Now they are manufactured, so they're human made, and they're usually from fossil fuels.

So first one is polyester.

Now, if you're wearing a blazer right now, or you normally wear a blazer to school, it's normally made from polyester.

That's because it's lightweight, it's durable, it's resistant to shrinking or wrinkles.

So I bet you don't iron or I bet nobody irons your blazer for you.

Example products include sportswear, multiple clothing uses such as your blazers, carpets, sleeping bags.

Next up is ripstop nylon.

Now this is often used in kites and tents because it's lightweight, but also tear resistant.

Quite often my students find it really weird that they're wearing a polymer.

And it is quite a strange thought when you think of it like that, isn't it? Next up are mixed or blended fibres.

These are exactly what they say.

They're mixed or blended to create that fibre.

They're normally mixed to improve the fabric in some way.

So a great example is polyester cotton, which is the blend of polyester and cotton.

It's breathable just like cotton, but it's also crease resistant just like polyester.

So it brings two fantastic properties to the table, or to the product, or to the bits of clothing, and a great example of that are shirts.

Identify the materials that originate from fossil fuels, A, HDPE, B, PLA, C, ripstop nylon, and D, wool.

Come back to me when you've got an idea.

Well done if you managed to identify A and C.

Both of those two are made from fossil fuels.

Remember, wool is a naturally-occurring textile, and PLA is a biodegradable polymer made from something like corn starch.

Onto task B.

There are three pictures of products on the left-hand side.

We have the woolly hat, the kite, and then the wheelie bins.

What I'd like you to do is, first of all, identify what properties those products would need.

And then I've given you three different options for materials.

I would then like you to pick, based on the required properties, the most suitable material.

Have go.

Good luck.

Come back to me when you've got some answers.

Let's take a look at our answers.

So for the hat, you want it to be soft and insulating to keep you nice and warm in the winter, and the best choice would be wool.

Next up, kite, you want it to be lightweight and tear resistant in case it gets stuck in a tree, and a great choice is ripstop nylon.

And lastly, for the wheelie bins, you want it to be lightweight, impact resistant, and chemical resistance because you are going to have a whole load of things thrown into that bin with different chemicals as well and different foods.

You want it to be able to protect itself from that, and the best choice would of course be HDPE.

The image shows a teddy.

It is made from cotton which is a natural fibre.

Part two, give two reasons why cotton is suitable.

Next up, the closed peg on the right-hand side at the bottom is made from materials from two different categories.

You're gonna have to look quite closely.

So for part three, I would like you to identify the two material categories, and then suggest a suitable material from that category and explain why each has been chosen by yourselves.

Good luck.

Have a go.

Come back to me when you've got some answers.

Let's take a look at our answers.

So for part two, cotton is a natural material which is soft and unlikely to cause irritation for small children.

It is also easily washable, making it a perfect choice for a teddy bear.

Part three, the clothes peg is made of two different material categories.

First of all, a polymer.

Now, it's likely to be a thermo polymer, such as HDPE, as it is lightweight so as not to add extra weight to the washing line, and it's also impact resistance as pegs are frequently dropped.

And then metal, non-ferrous, such as stainless steel.

Now, that's for the little spring inside so that the peg can open and close.

Stainless steel will be a great choice so that it does not wear with the wet clothes or when they are accidentally left outside in the rain, which I do do a lot.

Well done with all of your efforts there.

This brings us to the end of our lesson today.

Let's summarise what we have found out.

Timber categories include hardwoods, softwoods, and manufactured boards.

Metal categories include ferrous, non-ferrous, and alloys.

Paper and boards are available in a range of weights and thicknesses.

Polymer categories include thermo and thermosetting polymers.

Textile categories include natural and synthetic fibres.

Within these categories are naturally occurring materials and those which are manufactured.

Materials are chosen depending on the working and/or physical properties that the product requires.

Well done with all of your hard work and all of your efforts today, and I hope to see you again in another lesson soon.

Take good care.

Bye bye bye.