How many centimetres of rope will I need to make another mat just like the one I have here?

The area of a square inscribed in a circle with a unit radius is, satisfyingly, 2. What is the area of a regular hexagon inscribed in a circle with a unit radius?

How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?

In this game for two players, you throw two dice and find the product. How many shapes can you draw on the grid which have that area or perimeter?

An investigation that gives you the opportunity to make and justify predictions.

What can you say about these shapes? This problem challenges you to create shapes with different areas and perimeters.

What are the areas of these triangles? What do you notice? Can you generalise to other "families" of triangles?

Polygons drawn on square dotty paper have dots on their perimeter (p) and often internal (i) ones as well. Find a relationship between p, i and the area of the polygons.

It's easy to work out the areas of most squares that we meet, but what if they were tilted?

Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.

What happens to the area of a square if you double the length of the sides? Try the same thing with rectangles, diamonds and other shapes. How do the four smaller ones fit into the larger one?

Look at the mathematics that is all around us - this circular window is a wonderful example.

A red square and a blue square overlap so that the corner of the red square rests on the centre of the blue square. Show that, whatever the orientation of the red square, it covers a quarter of the. . . .

This rectangle is cut into five pieces which fit exactly into a triangular outline and also into a square outline where the triangle, the rectangle and the square have equal areas.

Identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?

Can you draw a square in which the perimeter is numerically equal to the area?

How can you change the area of a shape but keep its perimeter the same? How can you change the perimeter but keep the area the same?

Seven small rectangular pictures have one inch wide frames. The frames are removed and the pictures are fitted together like a jigsaw to make a rectangle of length 12 inches. Find the dimensions of. . . .

What is the largest number of circles we can fit into the frame without them overlapping? How do you know? What will happen if you try the other shapes?

If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?

Have a good look at these images. Can you describe what is happening? There are plenty more images like this on NRICH's Exploring Squares CD.

Draw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?

Can you help the children find the two triangles which have the lengths of two sides numerically equal to their areas?

How many ways can you find of tiling the square patio, using square tiles of different sizes?

Semicircles are drawn on the sides of a rectangle ABCD. A circle passing through points ABCD carves out four crescent-shaped regions. Prove that the sum of the areas of the four crescents is equal to. . . .

I'm thinking of a rectangle with an area of 24. What could its perimeter be?

These rectangles have been torn. How many squares did each one have inside it before it was ripped?

A thoughtful shepherd used bales of straw to protect the area around his lambs. Explore how you can arrange the bales.

Investigate all the different squares you can make on this 5 by 5 grid by making your starting side go from the bottom left hand point. Can you find out the areas of all these squares?

Can you find rectangles where the value of the area is the same as the value of the perimeter?

This practical challenge invites you to investigate the different squares you can make on a square geoboard or pegboard.

My local DIY shop calculates the price of its windows according to the area of glass and the length of frame used. Can you work out how they arrived at these prices?

A follow-up activity to Tiles in the Garden.

Cut differently-sized square corners from a square piece of paper to make boxes without lids. Do they all have the same volume?

These practical challenges are all about making a 'tray' and covering it with paper.

What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?

What is the smallest number of tiles needed to tile this patio? Can you investigate patios of different sizes?

Investigate the area of 'slices' cut off this cube of cheese. What would happen if you had different-sized block of cheese to start with?

What do these two triangles have in common? How are they related?

Grandpa was measuring a rug using yards, feet and inches. Can you help William to work out its area?

Can you work out the area of the inner square and give an explanation of how you did it?

I cut this square into two different shapes. What can you say about the relationship between them?

This article for teachers gives some food for thought when teaching ideas about area.

Nine squares with side lengths 1, 4, 7, 8, 9, 10, 14, 15, and 18 cm can be fitted together to form a rectangle. What are the dimensions of the rectangle?

What shape has Harry drawn on this clock face? Can you find its area? What is the largest number of square tiles that could cover this area?

You have pitched your tent (the red triangle) on an island. Can you move it to the position shown by the purple triangle making sure you obey the rules?

Choose a box and work out the smallest rectangle of paper needed to wrap it so that it is completely covered.

How would you move the bands on the pegboard to alter these shapes?