Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.
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?
It's easy to work out the areas of most squares that we meet, but
what if they were tilted?
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?
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.
How many centimetres of rope will I need to make another mat just
like the one I have here?
How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?
An investigation that gives you the opportunity to make and justify
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?
These practical challenges are all about making a 'tray' and covering it with paper.
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.
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 find rectangles where the value of the area is the same as the value of the perimeter?
How many ways can you find of tiling the square patio, using square
tiles of different sizes?
Can you maximise the area available to a grazing goat?
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?
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?
Cut differently-sized square corners from a square piece of paper
to make boxes without lids. Do they all have the same volume?
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. . . .
If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?
Can you draw a square in which the perimeter is numerically equal
to the area?
What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?
These rectangles have been torn. How many squares did each one have
inside it before it was ripped?
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. . . .
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?
Explore one of these five pictures.
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.
A thoughtful shepherd used bales of straw to protect the area
around his lambs. Explore how you can arrange the bales.
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?
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?
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?
This practical challenge invites you to investigate the different
squares you can make on a square geoboard or pegboard.
What is the smallest number of tiles needed to tile this patio? Can
you investigate patios of different sizes?
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
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?
This article for teachers gives some food for thought when teaching
ideas about area.
Look at the mathematics that is all around us - this circular
window is a wonderful example.
I cut this square into two different shapes. What can you say about
the relationship between them?
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 tiles do we need to tile these patios?
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.
Explore this interactivity and see if you can work out what it
does. Could you use it to estimate the area of a shape?
Grandpa was measuring a rug using yards, feet and inches. Can you
help William to work out its area?
A simple visual exploration into halving and doubling.
What do these two triangles have in common? How are they related?
How would you move the bands on the pegboard to alter these shapes?