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?
It's easy to work out the areas of most squares that we meet, but
what if they were tilted?
What are the areas of these triangles? What do you notice? Can you generalise to other "families" of triangles?
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?
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. . . .
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?
If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?
Can you find rectangles where the value of the area is the same as the value of the perimeter?
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.
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.
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. . . .
Use the interactivity to find all the different right-angled
triangles you can make by just moving one corner of the starting
Can you maximise the area available to a grazing goat?
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. . . .
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 can you say about these shapes? This problem challenges you to
create shapes with different areas and perimeters.
An investigation that gives you the opportunity to make and justify
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?
Can you work out the area of the inner square and give an
explanation of how you did it?
These practical challenges are all about making a 'tray' and covering it with paper.
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.
Can you draw a square in which the perimeter is numerically equal
to the 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?
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?
What is the largest 'ribbon square' you can make? And the smallest? How many different squares can you make altogether?
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
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?
A task which depends on members of the group noticing the needs of
others and responding.
Can you help the children find the two triangles which have the
lengths of two sides numerically equal to their areas?
An activity for high-attaining learners which involves making a new cylinder from a cardboard tube.
A follow-up activity to Tiles in the Garden.
Explore one of these five pictures.
I'm thinking of a rectangle with an area of 24. What could its perimeter be?
This article, written for teachers, discusses the merits of different kinds of resources: those which involve exploration and those which centre on calculation.
In the four examples below identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?
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
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
Choose a box and work out the smallest rectangle of paper needed to
wrap it so that it is completely covered.
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
What fractions of the largest circle are the two shaded regions?
These rectangles have been torn. How many squares did each one have
inside it before it was ripped?
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).
This practical challenge invites you to investigate the different
squares you can make on a square geoboard or pegboard.
Determine the total shaded area of the 'kissing triangles'.
Derive a formula for finding the area of any kite.
Cut differently-sized square corners from a square piece of paper
to make boxes without lids. Do they all have the same volume?
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. . . .
Make an eight by eight square, the layout is the same as a
chessboard. You can print out and use the square below. What is the
area of the square? Divide the square in the way shown by the red
dashed. . . .