Lesson video

Hi there, everybody, my name is Mr. Booth and welcome to your design and technology lesson for today.

In today's lesson, we are going to be looking at a wonderful material that we have used for thousands of years to build our products and our homes.

You will come into contact with this material on a daily basis, and in fact, you've probably already come into many different types of this material already today.

I'm obviously talking about wood, and today we're gonna be looking at wood functional properties and what makes it such a wonderful material for us to use when we make our products.

This lesson is part of the Cams: automata unit.

Today's outcome: I want you to be able to explain the difference between soft and hard woods and also then be able to make choices about the woods that we use and why we use those different types of woods for the products that we make.

So we have five keywords today and I want you to look out for these throughout the lesson.

The first two are about the types of trees we are gonna be looking at.

The first is, of course, deciduous.

These are trees and shrubs that lose their leaves every single year.

So as we approach autumn, many of their leaves will turn brown, they'll fall out of the trees, but then of course they come back in spring.

We then have evergreen.

These are trees and shrubs that do not lose their leaves.

Their leaves stay green all year round.

We then have two different types of woods that we get from these trees.

The first is hardwood, wood from trees that lose their leaves in the autumn.

So these deciduous trees.

And then we have the soft woods.

And the softwoods tend to come from trees that keep their leaves all year round.

And the final keyword, which is really important when we're talking about wood and timber and making products is, of course, grain.

This is the pattern seen in the wood when it has been cut.

We have two learning cycles today.

The first is the properties of hardwoods and softwoods.

The second is all about hardwood and softwood timber products.

So let's get going on the first learning cycle.

Wood is a renewable, natural material that has been used throughout history for many different purposes.

We've used it for thousands of years: fuel for our fires, to make our homes, to make the furniture that goes in our homes, and, of course, to make structures such as bridges to cross streams or rivers.

Now before we go any further, I want you to tell me what does renewable mean?

You might wanna do it in this context of wood.

So pause the video now, have a chat to the person next to you and see if you can decide what renewable might mean.

Okay, did you remember?

I'm sure you did.

Of course, renewable means we can always grow more trees, we can renew them.

That's why it's a renewable resource.

Now can you think of any more areas or products that we have made using wood?

Pause the video now have a little think about that, see if maybe you could write some down, any other things that we make out of wood.

So did you think of any?

I'm sure you thought of absolutely loads.

Even just looking around the room that you are in now.

I've got some here.

So we have things like weapons or tools.

If you're in a design and technology workshop, you might be able to see lots of tools where the handles are made of wood.

Toys, of course.

There are lots of toys made of woods.

There might be different transport.

Here we have a cart, or it could be something like art.

So lots of different things that we make using woods.

Now, woods can be grouped into two different types.

We have hardwood and softwoods.

Obviously two of our really key words there.

The type of wood depends on the tree that it comes from.

So let's have a closer look at some of these.

Hardwood timbers usually come from slow growing, deciduous trees.

Now obviously we've got two of our keywords there, hardwoods and deciduous.

It's important that we remember that those two go together.

Some examples of these are oak, beech, ash, mahogany and walnut.

Now there's a good chance that actually you've probably seen an oak tree at some point in your lives.

They're very beautiful.

They are a slow growing hardwood.

That is a deciduous tree.

So of course it will lose its leaves when it comes to autumn.

Deciduous trees have broad, which means wide, and flat leaves that, of course, turn brown and fall off in the autumn and winter.

And you can see an image there.

Now some trees actually do naturally have kind of brownish or reddish colored leaves.

But most of these deciduous trees, it will turn brown in the autumn.

we know winter is coming, and, of course,, they will then fall.

Deciduous trees have a tight, close grain.

That's the pattern that you can see in the wood once you cut through it.

And this makes them a lot harder to cut.

Now, all wood can have knots.

These are the circular patterns that you often find and this is where branches used to grow.

And as the tree grows, it kind of en encompasses these and you get knots within the wood.

I think they're quite beautiful when you see the knots within a product.

Because hardwoods take longer to grow and have a close grain, they are often much stronger and durable than softwoods.

And if you look at the rings, these are the stages of growth.

So you can see the different seasons there within the tree.

And the closer they are together, then the stronger obviously that material is gonna be.

It's gonna be more dense.

Slow growth makes the grain pattern tight so the wood becomes stronger.

It's exactly what I've just said.

Now, some hardwood trees can take over 100 years to mature, to get to the size they need to be so we can cut them down and use them for our product.

This means it takes much longer to replace them.

So they usually have a higher cost compared to softwoods because of course we've gotta look after them for 100 years.

So that's amazing.

So if you try and plant an oak tree now, there's a good chance it's your grandchildren that would be able to use it.

Isn't that amazing?

And if we compare that to softwood trees, they can usually be replaced in 20 to 40 years.

So they grow much quicker, again making them cheaper.

Now we've got Alex here.

He says, "Some hardwood trees can take up to 250 years to grow.

" And in fact, some of the oldest trees in the world are even older than that.

Thank you, Alex.

Quick check for understanding.

How long do softwood trees take to grow?

Is it A: zero to 20 years?

B: 20 to 40 years?

C: 40 to 60 years?

or D: 100 years plus, more than a hundred years?

And when I say grow, of course, I mean how long does it take them get to a point where we can cut them down and use them for our products?

Pause the video now, have a go at this.

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

It is, of course, B, 20 to 40 years.

Well done.

Now, whilst they are known for their strength and durability, not all hardwoods are dense and hard.

For example, if you have used balsa wood, that is a very light and soft wood.

You can break it in your hands.

But it comes from a deciduous balsa tree and it's often used for model making.

For example, here we can see Alex has made a balsa aeroplane with his sister, because it's so lightweight and it actually might fly if you put a motor in it.

Quick check for understanding.

True or false?

The close grain in most hardwoods is what makes them strong.

Is that true or is that false?

Pause the video now, have a go at this.

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

It is, of course, true.

But why?

I want you to pause the video again.

Have the chat with the person next to you and come up with an answer as to why that is true.

Okay, and, of course, it is because the slow growth makes the wood more dense.

Those rings are tighter together.

So it's stronger because there is less room for flexibility and that makes the products more robust.

So let's look at softwoods now.

So softwood timbers come from a small group of fast growing evergreen trees that have needles and cones.

Coniferous we call this, or conifers you might have heard of before.

Some examples are pine, cedar, fur larch, and, of course, yew, and I'm sure you have at some point, seen a pine tree somewhere.

They're very common.

And there you have a nice example of seeing the needles and the cones and those needles, they stay on the tree all year round and they stay green.

These types of evergreen trees usually have needles and cones instead of leaves and they stay green all year round, just as I have said.

Now they have a loose grain.

So you can see the pattern in the wood here when compared to our oak tree, okay, it's a lot looser.

That makes them a lot easier to cut.

And actually, in your school lives, you will use pine quite a lot.

And one of the reasons for that is, of course,, because it's easier to work with.

Just like hardwood, it can contain knots as well.

So all trees tend to contain knots.

And this again is where the branches once grew.

But again, I quite like them.

I think they give the wood character.

Now, because softwoods have quick upward growth and a loose grain, they are more sustainable but less durable than hardwoods.

And you can see here we have a pine forest and this is probably a managed pine forest.

So it's planted by us, it's probably not a natural one.

And they have long, straight trunks, which is great for us because we can make those into things like planks to use in our products.

Now the quick growth makes the grain loose so the wood is softer, easier to work with.

Quick check for understanding.

Which of these would be a softwood tree?

Look at these three images.

So we have image A, image B, and image C.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is, of course, B and that is because it's from a conifer.

It's got needles, it's got cones.

And if you look at A, well that's our oak tree and you can see there, we've seen that before.

And also C, the leaves have turned brown.

It's autumn, which means they're probably gonna fall off soon, which, of course, means it's a deciduous tree.

Well done.

Now, whilst softwoods are known for their flexibility and loose grain, not all of them are soft and light.

For example, yew is actually a heavy and hardwood that comes from our coniferous softwood yew tree.

Now traditionally it was used to make tools and weapons which needed to withstand heavy use.

So you can see here we've got an axe handle, but also we have quite a flexible bow from from a weapon.

Quick check for understanding.

True or false?

all hardwoods are hard and softwoods are soft.

Think about it carefully pause the video now and come back to me when you've got your answer.

It is, of course, false.

Now why?

And have a think about it and you might wanna use some examples in your why.

So pause the video now.

Come back to me when you know why.

Well, it is, of course, because balsa is very soft and light, but it's from a deciduous hardwood tree.

And yew is heavy and hard, but it's from a coniferous softwood tree.

Brilliant.

So we're now onto your first task.

What I would like you to do is sort the properties of hardwood and softwood.

Using the template, cut out and sort the cards on the next slide into two groups, hardwoods and softwoods.

I would like you to think about the types of tree they come from and their characteristics, what makes them hardwoods or softwoods.

So let's have a look at what you're gonna be using.

So here are your examples.

So you can see some of it relates to how it grows, some of it relates to the characteristics that are used when we actually make the products.

So I want you to sort these into softwoods and hardwoods.

Pause the video now, have a go at this and come back to me when you've completed the task.

So how did you get on?

Well, I'm sure you managed it and hopefully you had a good conversation with your neighbor when you were doing this task as well.

So I asked you to sort the properties of hardwoods and softwoods.

So let's have a look at hardwoods first.

They have a close grain.

They're quite expensive 'cause, of course, they take a long time to grow.

They come from a deciduous tree.

They're durable.

Light, soft balsa wood is also a hardwood.

They tend to have broad leaves.

They're slow growing and they have wide trunks.

Brilliant.

Softwoods, on the other hand, have a loose grain.

They're more affordable 'cause they grow quicker.

They come from coniferous trees.

They're sustainable because we can grow them very, very quickly.

They're more sustainable than hardwoods.

They are hard and heavy if it's a yew tree.

They're evergreen, so they keep their green needles all the year round.

They're quick growing and they tend to have long, straight trunks, which are obviously great for making products.

Well done with that task.

Now onto our next learning cycle.

Hardwood and softwood timber products.

So wood that is specifically grown and used for manufacturing is referred to as timber.

So we've talked about trees, so we know what trees are.

We've talked about wood, which is what we get from trees, but now we're actually gonna turn it into a product.

So what we tend to call the material is timber.

That's the difference between those three terms.

And if we have a look at the process of how we actually do this, well, first of all we of course, have to fell those trees to collect the raw material, which of course, is the wood.

Now gone are the days when we do this with an axe.

We tend to do it with chainsaws or even heavy machinery can do this now.

The logs are then sent to be processed, and you can see on the back of this very heavy lifting vehicle here, They then go through lots of different cutting stages and that's then used as a timber.

And this is how we can then make our products.

Quick check for understanding.

Which word is used to describe wood that is to be used to make things?

Is it A: resin, B: timber or C: fibers?

Pause the video now have a go at this and come back to me when you've got your answer.

It is, of course, timber.

That is the material we are gonna use to make our products.

Well done.

Hardwood timbers are typically used to make products that are decorative, durable and long lasting.

Let's have a look at some of these.

So of course, we have musical instruments, very beautiful but also very expensive.

We have doors and window frames, especially if they're external.

So if they're being exposed to the weather, the outside.

And, of course, we have decorative furniture.

And you can see here we've got this very beautiful desk.

Softwood timbers are typically used to make products that are lightweight, cheap to buy and easy to replace.

Such as internal doors, which of course, don't have to withstand the weathering of external doors.

We also have things like garden sheds.

And also decking.

They tend to be softwood as well.

Softwoods are used to make paper and card products as well.

They're also good for using in the building industry.

So paper is made from pulped softwoods 'cause it's easier to process since it's cheaper.

And, of course, long, straight trunks make it really good building material.

The roof above my head right now has softwood timber struts in there to hold it up.

Quick check for understanding.

Why are external windows and doors often made from hardwood?

Is it A: they're more durable in all weathers?

B: easier to cut and shape?

Or C: more affordable?

Pause the video now, have a go at this and come back to me when you've got your answer.

It is, of course, they are more durable in all weathers.

Again, it's because of that close grain.

The type of timber chosen to make a product depends on the user, the function, and, of course, the affordability, the cost of the product and how to make it.

Some products can be made from either hard or soft woods.

Here we have a softwood side table.

So this might be used next to a bed or it could be used in a living room to put your TV remote control on.

But we could also have a hardwood side table as well.

And you can see this is far more decorative but also would be more expensive but more durable.

Now Izzy has been looking at products made from hardwoods and softwood timbers.

So let's see what Izzy says about this side table.

"This table is made of softwood.

It is a simple design and it was quick to produce because the loose grain makes it easy to shape.

This makes it more affordable.

The wood is soft so it could get scratched or marked, but it could be easily replaced because of the low cost.

" Thank you, Izzy.

Now she's compared the first product to a similar one made from a different timber.

Let's see what Izzy says about this side table.

"This table is made of hardwood.

It has a decorative design, so it would take more time to produce, which makes it more expensive.

It is more durable because of the close grain which makes the wood stronger.

It would be harder to replace because of the cost and the fact that they are made in fewer numbers.

" Brilliant, Izzy, that's a great comparison.

Check for understanding.

Why are softwoods more affordable?

Is it A: they have straight trunks, B: they are evergreen, or C: they grow quickly?

Pause the video now have a go at this and come back to me when you've got your answer.

Well the obvious answer is, of course, they grow quickly, but we could also say it's because they have straight trunks, which actually makes them far easier to process, which again reduces the cost when compared with some hardwood alternatives.

Well done.

So we're now onto Task B.

First of all, I want you to explain why building materials are often made from softwoods.

And you can see here we've got that roof structure.

I then want you to explain why external outside doors and window frames are often made from hardwoods.

Have a go at this task, come back to me when you have got your answers.

Pause the video now.

So how did you get on?

Well, let's have a look at some example answers.

Well, first of all, softwood timber is often used in the building trade because it provides long, straight planks.

It's more affordable to buy and it's easier to cut and shape on the building site because it has that loose grain.

External doors and window frames need to be hard-wearing and durable because they are exposed to all types of weather and they provide protection.

The close grain of hardwood makes it stronger and therefore more suitable for this.

How did you get on?

I'm sure you got something similar.

Well done.

Next part of this task, this product is made from hardwood, it's an outdoor climbing frame.

Can you explain, using the properties that you have learned about today, why this wood might be chosen to make this product?

Pause the video now, have a go at this and come back to me when you've got your answer.

Well, how did you get on?

Well, here are some of my key reasons.

First of all, it's durable.

It's exposed to all weathers.

It's left outside.

It's not put away at the end of the day.

So because of that it's got to be durable.

It's hard-wearing.

Lots of children and possibly even adults will be climbing on these structures day after day.

So it's gotta be suitable for heavy use.

The close grain makes it a dense hardwood, which means it's less likely to be damaged.

And, of course, it needs to last a long time.

And because it's a hardwood, it will last for years.

And the final part of this task, this product is made from softwood.

This is a delivery pallet.

So if you ever have a lot of things delivered, but these are usually used in industrial settings.

What they do is they place all the products on top of one of these.

So it can be easily moved around, usually by a forklift truck.

So can you explain, using the properties you've learned today, why this wood was chosen to make this product?

The softwood.

Pause the video now, come back to me when you've got your answer.

So how did you get on?

Well, let's have a look at some key reasons why this pallet, this delivery pallet was made from softwood.

Well, first of all, it's low-cost.

We actually make lot of these pallets every single year.

Large quantities will be needed.

It's lightweight, which means it won't add to the weight of delivery vehicles, which of course adds a cost.

The loose grain makes it soft so it can be very easily cut, shaped and assembled, which means you can make lots of these very quickly.

How did you get on?

I'm sure you did a fantastic job just as well.

So that brings us to the end of this lesson.

Let's have a quick summary about wood functional properties.

Hardwood and softwood come from different types of trees.

Softwoods are usually cheaper to purchase and more sustainable as they are quicker to grow.

Softwoods can be easier to shape and change.

Hardwoods are usually stronger and more durable.

You have been absolutely brilliant today.

I hope you've enjoyed today's lesson and what I really hope is that you can use lots of this knowledge when you come to deciding what to make your products out of.

Well done.