Lesson video

Hi, I'm Mrs. Dennett and in today's lesson, we're going to be looking at Venn diagrams. We're going to find out how to sort data and label Venn diagrams correctly.

We'll start by using Venn diagrams to sort data.

Have a look at the Venn diagram here.

There are two circles, one labelled blue and the other labelled triangle.

The circles overlap.

Why do you think that is? Is because we might have a shape that's blue, and a triangle.

There's also a rectangle around the two circles.

This is the universal set, also represented by this Greek letter.

It's all of the data we're dealing with, in this case, all these shapes.

The Greek letter goes at the top left of the diagram, and all of the data is within the rectangle and the circles.

When completing a Venn diagram, it's best to start with the overlap.

That's this yellow section here.

This section represents shapes that are blue, and a triangle.

So we put the blue triangles into the overlap.

Now we look at the remaining section of the blue circle.

This is the shapes that are blue, but not triangles.

I can then look at the remaining section of the triangle circle.

I can put triangles in here.

Let's put the red triangle in there.

The two green circles are going to go in the box outside the circles as they're neither blue nor a triangle.

Another term to be aware of is that we call each piece of data in the Venn diagram, an element or a member of the set.

Here is a question for you to try.

Pause the video to complete the task and restart when you are finished.

Here is the answer.

The elements of A and B go in the overlap.

That's to say the middle section of the diagram.

Now we're going to represent some numerical data in this Venn diagram.

Pause the video and have a go, restart when you are finished.

Here is the answer.

Did you remember to start with the overlap? The overlap contains the numbers that are odd and a factor of 12.

So we can put one and three in here.

Look at the remaining section of the odd circle.

Put in five, seven and nine.

Look at the remaining section of the factors of 12 circle.

We have two, four and six that are factors of 12.

These numbers were not odd, so they only got in the factor of 12 circle, not in the overlap.

I have eight and 10 left in my universal set.

So they can go in this part of the Venn diagram.

Inside the rectangle, but not inside the circles.

Here is the Venn diagram again.

We're asked to list the elements of the universal set.

We do this using curly brackets, and include all the elements or members of the universal set.

We list all of the numbers in the Venn diagram.

You can put these in any order.

Here is the Venn diagram again.

We're told that set A is the set of odd numbers and asked to list the elements or members of set A.

Again, we do this using curly brackets and include all of the elements in the circle labelled odd.

That is, all of the numbers in that circle.

So we write A equals curly bracket, one, three, five, seven, nine, close curly bracket.

Here is a question for you to try.

Pause the video to complete the task and restart when you are finished.

Here are the answers.

The members of the universal set are all of the numbers in the diagram.

For the members of set B, we only look for numbers in circle B.

These numbers are two and four.

Here's a question for you to try.

Pause the video to complete the task and restart when you are finished.

Here's the answer.

Start with the overlap.

One and three are in both sets A and B.

Then look at the remaining section of circle A.

Five, seven and nine go in here.

Do the same for the remaining part of circle B.

Check that we haven't missed any numbers from the universal set that would go inside the rectangle, but not inside the circles.

In this question, there aren't any.

So we're finished.

Here is another question for you to try.

Pause the video, complete the task and restart when you are finished.

Here is the answer.

Check that your numbers are in the correct sections.

We're then asked to list the elements of B.

Look at all of circle B.

We have three, six and 12 in the overlap, and one, two and four.

We use curly brackets to list these numbers.

Remember that the order doesn't matter.

Here is a question for you to try.

Pause the video to complete the task and restart when you're finished.

Here are the answers.

Did you recognise the prime numbers in set A? And then notice that all of the members of set B are even numbers.

Here is a final question for you to try.

Pause the video to complete the task and restart when you are finished.

Here are the answers.

There are no common members of sets A and B.

So this question illustrates how not all Venn diagrams, have to have an overlap.

Neither do Venn diagrams only have two circles, you can have three or more circles.

But that's for a different lesson.

That's all for this lesson.

Remember to take the exit quiz.

Thanks for watching.