Lesson video

Hello, my name's Mr. Davidson.

I'm so pleased that you've decided to complete your learning with me today.

We are going to do brilliantly.

Today's lesson is called "Making groups", from the unit "Organising data using databases".

We're going to work really hard together today, but I'm here to help, and we can learn together.

By the end of today's lesson, you're going to be able to identify the attributes needed to collect data about an object.

There are gonna be two keywords that are gonna appear throughout the lesson.

The first is "group", which we define as a set of people or objects placed together.

The second is "branching tree diagram".

Now that's a diagram where data is organised into a structure that's like an upside-down tree.

You'll see how we use these later in the lesson.

The lesson is split up into two parts today.

Let's start with the first, where we're going to select an attribute to separate a group of objects.

Now, firstly, let's try and think back to what we already know about groups and their attributes.

Remember that an attribute is a word or a phrase that can be used to describe an object, such as its colour.

In this example, I've got a pencil, and it's red.

So the attribute for that pencil is that its colour is red.

I might have a second pencil.

Again, I could use the colour attribute.

But this time, we would say that its attribute for colour is green.

And that continues for however many pencils we want to look at.

In this case, I have a blue pencil.

We might describe an object using a different attribute.

Perhaps we could use size.

For example, I might be looking at the attributes of different animals.

If I've got an elephant, I would say that its attribute for size is big.

And I would also say that if I had a mouse, its size attribute would be small.

We're not limited to any particular attribute as long as our group of objects have those particular attributes in common.

A third example might be price.

I might have a teddy bear, and its price is three pounds and 99 pence.

Again, that would change for different objects in that group, but we could always compare them by the price that we are charging people to buy them for.

So let's try and put that into a sentence.

Use the keywords that we've got at the bottom to complete the sentence so that it makes sense.

Well done.

An attribute is a word or phrase that could be used to describe an object, such as its colour, size, or price.

So we've thought about the attributes of different objects.

I've given you some more objects here, and I want you to think about what attributes you could use to separate these objects into groups.

So what attributes could you have used? A good starting point would be to see if the animal that we're looking at has legs.

In our picture, we can see that some animals do and some don't.

That would mean that any of the fish in our group would be eliminated because they don't have legs.

We could have used a different attribute, such as, is it a farm animal? Again, our fish are not considered farm animals, so they wouldn't belong to the group.

We've created two similar groups, but each of the two groups have different attributes.

A third one might be, has scales as an attribute.

That would mean this time, the fish are selected, and all the other animals are not considered part of that group.

So let's try and think about that in a bit more detail.

I want you to fill in the missing questions and attributes based on the object below.

So that object is a spanner, and I've given you an example at the top of the table.

If I was asking a yes no question about that object, my first question would be, is it a spanner? It either is or it isn't.

And I would link that to the attribute called "type of object".

By asking that yes no question, I am actually determining what the type of object is.

What can we use, though, for the places where I've marked with question marks? Have a think for a moment.

So we have our spanner, and we're going to ask, firstly, another yes no question, and to find out what material that spanner is made from.

I think a sensible yes no question would be, is it made of metal? I can either answer yes or no, and if I answer yes, that would mean that the material attribute is metal.

If I answer no, then it's some other material.

I have another yes no question following that.

Is it smaller than a car? That's a yes no answer.

And I'm saying is it smaller than a car? So I would say that the attribute there is to do with size.

Lastly, a yes no question could be, is it grey? Grey is what we are measuring, whether it is or isn't grey.

So our attribute for that object is colour.

I'm gonna want you to have a go with these objects now.

So think of all of those examples that we've just seen.

I'm gonna want you to select an attribute that separates those objects into similar sized groups.

Have a think about other attributes that you could use.

There are so many possible attributes, we're all going to get different answers, but we've got to remember that when we ask the questions to find out about those attributes, they either have them or they don't.

So we need yes no questions.

I want you to pause the video and have a go now.

When you come back, we'll try some of the examples that I have, but bear in mind, the examples won't necessarily be the same as yours.

Well done.

There were lots of great answers with that.

When I was selecting my attributes to separate these objects into similar sized groups, the first one that I did was "has horns", and if I looked across all of the different monsters, the first monster doesn't, the fourth monster doesn't, the fifth monster doesn't, and that would mean the ones that were left do have horns.

My second attribute that I tried to group the monsters into was "has striped legs".

So again, we could ask that as a yes no question, and if I go through each of them in turn, the first one doesn't have striped legs, the third one doesn't, but the second one does.

The fourth one doesn't, but the fifth one does.

And then the last one doesn't.

So my groups are monsters with striped legs and monsters who do not have striped legs.

A final way I was going to group these monsters together was the attribute "claws".

So my yes no question was "does it have claws?" And again, working through each of the monsters, I can see that the second one doesn't have claws, but if we look at the first monster, we can see that it does.

So that's how we compare sets of data together, or sets of monsters together.

I carry on, asking myself if each monster has claws.

We can see there that the third one doesn't.

The fourth one does, but the fifth one doesn't, and then the last one doesn't have claws either.

So we're left with two monsters there that have claws.

We're now gonna carry on into the second part of today's lesson, where we're going to create a branching tree diagram.

And before we think about what a branching tree diagram is, let's just check again attributes that could separate these objects into two equal groups.

So by equal groups, what I'm trying to do is get the same number of objects in both groups.

Now, objects can't be in two different groups at the same time in these examples, so that means one group should have two objects, the other group should also have two objects.

Now think back to what we did earlier in the lesson.

What attributes could we use to separate them into equal groups? Have a think.

It might not be immediately obvious, so let's think through this example.

We have an aeroplane, a hot air balloon, a bicycle, and a motorbike.

If we pick an attribute, let's put them into those groups of has that attribute and doesn't have that attribute.

A most obvious one I can think of should be, can it fly? Our question, therefore, would be, "Does it fly?" It can either fly or not.

It's a yes no question.

And by answering that yes no question, we can work out the attributes of "can fly".

That means our two groups have a yes and a no answer to them.

And if I take the first one, the aeroplane, yes, it does fly.

And then secondly, the hot air balloon, it also flies.

So both of those have ended up in my yes group in answer to my yes no question.

As I then compare the other two objects, the bicycle.

Does a bicycle fly? I haven't seen many bicycles that do fly, so I'm gonna put it in the no group, and the motorbike, unless it's a famous film, no, I don't think motorbikes do fly in real life.

So I'm also going to put it in a no box.

There's nothing stopping us, either, being able to separate groups further.

So once we've agreed the first group about if they can fly, I could categorise them further by putting each of the ones in the yes group into their own separate groups again.

Can you think of any attributes both the aeroplane and the hot air balloon that are different between the two that we could use to separate them? So previously we asked, "Does it fly?" Where we got to these two objects in the group.

Remember that we can only ask questions with a yes no answer.

I've gone this time, the attribute "has wings".

One of the objects does, the other doesn't.

That would allow me then to separate those two objects into two different groups.

The aeroplane would have wings, the hot air balloon wouldn't have wings.

So in answer to our yes no question, that would split the group up further.

Let's just think about, then, how we got to that point.

We firstly asked the question, "Does it fly?" where we had a yes response, and we ended up with those two objects.

We ended up with the aeroplane.

We ended up with the hot air balloon.

The motorbike and the bicycle were in the no group, and so we don't consider them past this point.

Secondly, I asked, "Does it have wings?" We've got two groups there.

A yes, it does have wings, and a no, it doesn't have wings, but they're both objects that do fly.

The aeroplane ends up in the yes group, the hot air balloon ends up in the no group.

We could do that going back to the start with the no group.

What things do you think we could use to split up that no group based on the attributes that those two objects have? Let's think about that again then.

We have now our objects that do not fly.

They were in the no group.

Remember that we can only ask questions with a yes or a no answer.

I'm gonna consider the attribute "has an engine".

So to get to this point, we firstly asked for our four objects, "Does it fly?" This time our answer was no, and we ended up with a bicycle and the motorbike.

The second thing that we asked was, "Does it have an engine?" We therefore have two groups, a yes group, yes it does have an engine, and a no group, no it doesn't have an engine.

The bicycle therefore doesn't have an engine and will end up in the no group.

The motorbike ends up in the yes group because it's powered by an engine.

This structure is very important, because we are categorising our data to begin with by asking questions and grouping by similar attributes.

Each time that we decide to look at a different attribute, it creates a different part that we can follow and a different group that we can get to by asking the right questions.

We can represent this in something called a branching tree diagram.

We'd start with our first question, does it fly? Where we know that we have a yes response and a no response.

Objects that have the attribute "does fly", we're going yes.

Objects that do not have the attribute "does fly" would go in no.

Remember, an aeroplane and our hot air balloon ended up in yes.

The bicycle and the motorbike ended up in no.

We focus firstly on one side of the tree diagram now.

So let's focus on the yes part, and remember, we asked a second yes no question to work on a different attribute.

So we asked the yes no question, does it have wings? Because we wanted a group that has wings, and a group that doesn't.

Notice how both of them do fly, though, because we've ended up with this first group.

Our answer to our question, "Does it have wings?" is yes, or it's no, which means the aeroplane goes in yes, and the hot air balloon goes in no.

Both objects do fly, but one of the objects has wings, the other doesn't.

Let's now focus on the other side, on the no side.

We asked our question, does it have an engine? We have a yes and a no group.

The motorbike ended up in the yes group.

The bicycle ended up in the no group.

So both those two objects do not fly, but one has an engine, one does not have an engine.

We've now completed our branching tree diagram.

We don't need the boxes around them.

What we do need are the paths through, starting from our first question and following our yes no answers.

But we can see we've separated each of the objects into their own unique group based on three separate questions.

Now we've called that a branching tree diagram.

Can any of you spot why you think it's called a branching tree diagram? Well, let's think what a tree actually looks like.

We've got a tree that grows up from the ground.

We haven't put its roots on, but they would be there.

But we have the trunk of the tree, and all of the branches that grow from that main trunk.

Doesn't really look like our branching tree diagram yet.

But what about if we flip it upside down? We've got our trunk at the top, and all the branches that start to span off from that main trunk, from the root of the tree, essentially.

Think of our diagram and think of our upside-down tree.

You start to see there's similarities between the two, and that's where the diagram gets its name from.

It's a tree and it branches out.

In this case, if we had to describe our branching tree diagram, we would say the branching tree diagram shows the means of transport organised by questions with a yes or no answer.

So let's consider a second branching tree diagram.

Have a look through the objects that have been categorised by the diagram, and think what questions will have been asked before.

And your answers might be slightly different, and they may still work.

My answers were, is it an animal toy? That gives a yes or a no response.

And we can see there that on the left hand side of the diagram, we've got two animal toys.

So we could get to that point by following the yes branch.

Similarly, the two toys, the camper van and the robot, are not animal toys, and we could get to them through the no branch.

So that works.

The second question we could ask is, does it have wheels? So we could categorise the two further.

The camper van does have wheels, so we go down the yes branch, the robot doesn't, so it ends up in the no branch.

How about this one? What do you think the questions would be? Well, I'd start with, does it fly? So we've got two creatures that do fly, two creatures that don't.

And if we look at the ones that do fly, we would ask, does it have spots? One of the objects does, one of them doesn't, but they both do fly.

So we could get to those two objects by answering those two questions in the appropriate way.

You're going to have a go at that now.

I want you to use the images and the questions that I'm giving you to create your own branching tree diagram.

The objects are different dinosaurs, and the questions that I'm giving you are, does it have a fin or sail on its back? Does it walk on two legs? Does it fly? Does it have legs? Does it have stripes? Does it have a horn? Remember, you need to start with a yes no question that splits the objects into two similar size groups.

After each question, you should have roughly an equal amount of each of the objects.

We've got an even number of objects, so this should be possible.

Please pause the video and have a go.

It will be tricky at first, because you might not use all the questions in the right way.

Remember, your first answer might not be the one that you want to stick with, so don't be afraid to change some of the examples if you don't feel it's working.

Pause the video and have a go now.

Well done.

I think you did really well with that.

I've gone with, at the top, does it have a fin or sail on its back? Obviously we have yes no responses.

I chose that because there were three dinosaurs that did have a fin or a sail on its back, and three that didn't.

That left me with nice equal groups.

If I go down the yes branch to those ones with fins or sails on their backs, next I could have split them up into two different groups.

And because we're dealing with a group of three, that means my groups are gonna be slightly uneven from my second question, "Does it have legs?" So on the yes branch, I've still got two different dinosaurs, but on the no branch, I've only got one.

I probably don't need to ask any further yes no questions based on that, 'cause I've grouped my dinosaur there into its own group based on only two questions.

If I follow that down on the yes branch, I have to split them further, so I ask the third question, "Does it have a horn?" One does, one doesn't.

And that means my side of the diagram on the left hand side is complete.

I then started back at the top again.

Remember, at the root of the tree, where I asked, "Does it have a fin or sail on its back?" Where the no path led me to three different dinosaurs on the right hand side.

I asked the second question, "Does it fly?" Again, because I'm dealing with three, I'm not able to split them evenly.

But by asking "does it fly?" that applied to only one, where my yes branch ended up with the dinosaur that you see there.

The no branch ended up with two, so I needed a third question on the right hand side, "Does it have stripes?" where one does and one doesn't, which means I've now completed my diagram.

I could say that branching diagram categorises different dinosaurs by different attributes.

Well done.

You did really well today, and we learned a lot.

Let's just recap over what we saw.

Remember that objects can be described using their attributes.

Attributes then can be used to split objects into different groups.

Different objects are gonna have different attributes, and so therefore we can control by asking yes no questions about their attributes, which objects end up in different groups.

And lastly, we saw that objects can be arranged in something called a branching tree diagram, where we turned a tree upside down and its root, trunk, and branches, all spread out in the same way as our diagrams did in the activities.