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

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

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

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?

What is the total area of the four outside triangles which are outlined in red in this arrangement of squares inside each other?

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

Can you put these shapes in order of size? Start with the smallest.

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?

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

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?

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?

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?

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

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

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

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

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

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

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

Arrange your fences to make the largest rectangular space you can. Try with four fences, then five, then six etc.

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

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?

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

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

These pictures were made by starting with a square, finding the half-way point on each side and joining those points up. You could investigate your own starting shape.

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

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

A follow-up activity to Tiles in the Garden.

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?

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

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

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

A simple visual exploration into halving and doubling.

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

Measure problems for primary learners to work on with others.

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?

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

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

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

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

Investigate how this pattern of squares continues. You could measure lengths, areas and angles.

If I use 12 green tiles to represent my lawn, how many different ways could I arrange them? How many border tiles would I need each time?

This article, written for teachers, discusses the merits of different kinds of resources: those which involve exploration and those which centre on calculation.

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.

An activity for high-attaining learners which involves making a new cylinder from a cardboard tube.

Measure problems at primary level that require careful consideration.

Here are many ideas for you to investigate - all linked with the number 2000.

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?