In a previous activity, we used letters to represent unknown values and made expressions with them.

For example - 5 pens in a box with n boxes = 5n

This activity looks at other ways you might see this.

*You will need your knowledge of area and perimeter of shapes too!*

A question could look like this.

**Example **

Write an expression to represent the perimeter of this triangle.

__Answer__

The perimeter of the triangle is *'all the way round the shape!' we* hear you shout!

So, we add up all the sides, which gives us:

**a + b + c**

Let's have a look at another example.

**Example**

Write an expression to represent the area of this rectangle.

**Answer**

The area of the rectangle is *'width x height!' *we hear you shout!

So, we multiply the width by the height, which gives us:

**ab**

Now you have the hang of it - let's try some questions!