Can you rank these sets of quantities in order, from smallest to largest? Can you provide convincing evidence for your rankings?

My measurements have got all jumbled up! Swap them around and see if you can find a combination where every measurement is valid.

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.

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

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

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

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?

A simple visual exploration into halving and doubling.

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

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

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.

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

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?

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

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

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?

Points P, Q, R and S each divide the sides AB, BC, CD and DA respectively in the ratio of 2 : 1. Join the points. What is the area of the parallelogram PQRS in relation to the original rectangle?

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?

A hallway floor is tiled and each tile is one foot square. Given that the number of tiles around the perimeter is EXACTLY half the total number of tiles, find the possible dimensions of the hallway.

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.

Follow the instructions and you can take a rectangle, cut it into 4 pieces, discard two small triangles, put together the remaining two pieces and end up with a rectangle the same size. Try it!

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

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?

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?

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

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

A follow-up activity to Tiles in the Garden.

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

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

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?

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?

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

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

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

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

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

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

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

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

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

You have a 12 by 9 foot carpet with an 8 by 1 foot hole exactly in the middle. Cut the carpet into two pieces to make a 10 by 10 foot square carpet.

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

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?

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