Which is a better fit, a square peg in a round hole or a round peg in a square hole?

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?

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?

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.

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

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

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

A circle with the radius of 2.2 centimetres is drawn touching the sides of a square. What area of the square is NOT covered by the circle?

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

Read about David Hilbert who proved that any polygon could be cut up into a certain number of pieces that could be put back together to form any other polygon of equal area.

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.

Explore this interactivity and see if you can work out what it does. Could you use it to estimate the area of a shape?

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?

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?

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

Use the information on these cards to draw the shape that is being described.

A simple visual exploration into halving and doubling.

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

What happens to the area and volume of 2D and 3D shapes when you enlarge them?

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

What fractions of the largest circle are the two shaded regions?

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

At the corner of the cube circular arcs are drawn and the area enclosed shaded. What fraction of the surface area of the cube is shaded? Try working out the answer without recourse to pencil and. . . .

Bluey-green, white and transparent squares with a few odd bits of shapes around the perimeter. But, how many squares are there of each type in the complete circle? Study the picture and make. . . .

Determine the total shaded area of the 'kissing triangles'.

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

Investigate the different ways of cutting a perfectly circular pie into equal pieces using exactly 3 cuts. The cuts have to be along chords of the circle (which might be diameters).

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

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

Measure problems for primary learners to work on with others.

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

Measure problems for inquiring primary learners.

Measure problems at primary level that require careful consideration.

It is possible to dissect any square into smaller squares. What is the minimum number of squares a 13 by 13 square can be dissected into?

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

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

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

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?

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

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

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

Measure problems at primary level that may require determination.

A task which depends on members of the group noticing the needs of others and responding.

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

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

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?

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

Are these statements always true, sometimes true or never true?

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?

A follow-up activity to Tiles in the Garden.