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?
How have "Warmsnug" arrived at the prices shown on their windows? Which window has been given an incorrect price?
What can you say about these shapes? This problem challenges you to create shapes with different areas and perimeters.
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.
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 are the areas of these triangles? What do you notice? Can you generalise to other "families" of triangles?
Can you find rectangles where the value of the area is the same as the value of the perimeter?
An investigation that gives you the opportunity to make and justify
Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.
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.
Can you maximise the area available to a grazing goat?
It's easy to work out the areas of most squares that we meet, but
what if they were tilted?
If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?
How many centimetres of rope will I need to make another mat just
like the one I have here?
I'm thinking of a rectangle with an area of 24. What could its perimeter be?
Identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?
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?
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?
What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?
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. . . .
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?
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 rectangles have been torn. How many squares did each one have
inside it before it was ripped?
Can you draw a square in which the perimeter is numerically equal
to the area?
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 smallest number of tiles needed to tile this patio? Can
you investigate patios of different sizes?
These practical challenges are all about making a 'tray' and covering it with paper.
Cut differently-sized square corners from a square piece of paper
to make boxes without lids. Do they all have the same volume?
Choose a box and work out the smallest rectangle of paper needed to
wrap it so that it is completely covered.
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 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?
Do you know how to find the area of a triangle? You can count the
squares. What happens if we turn the triangle on end? Press the
button and see. Try counting the number of units in the triangle
now. . . .
Explore one of these five pictures.
You can move the 4 pieces of the jigsaw and fit them into both
outlines. Explain what has happened to the missing one unit of
This practical challenge invites you to investigate the different
squares you can make on a square geoboard or pegboard.
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
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?
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. . . .
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
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?
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 work out the area of the inner square and give an
explanation of how you did it?
A follow-up activity to Tiles in the Garden.
An activity for high-attaining learners which involves making a new cylinder from a cardboard tube.
What do these two triangles have in common? How are they related?
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.
How many tiles do we need to tile these patios?