Which is a better fit, a square peg in a round hole or a round peg
in a square hole?
A trapezium is divided into four triangles by its diagonals.
Suppose the two triangles containing the parallel sides have areas
a and b, what is the area of the trapezium?
Manufacturers need to minimise the amount of material used to make
their product. What is the best cross-section for a gutter?
Can you choose your units so that a cube has the same numerical value for it volume, surface area and total edge length?
A farmer has a field which is the shape of a trapezium as
illustrated below. To increase his profits he wishes to grow two
different crops. To do this he would like to divide the field into
two. . . .
If the base of a rectangle is increased by 10% and the area is
unchanged, by what percentage (exactly) is the width decreased by ?
What is the area of the quadrilateral APOQ? Working on the building
blocks will give you some insights that may help you to work it
Straight lines are drawn from each corner of a square to the mid
points of the opposite sides. Express the area of the octagon that
is formed at the centre as a fraction of the area of the square.
What happens to the area and volume of 2D and 3D shapes when you
Investigate the properties of quadrilaterals which can be drawn
with a circle just touching each side and another circle just
touching each vertex.
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?
Three rods of different lengths form three sides of an enclosure
with right angles between them. What arrangement maximises the area
Four quadrants are drawn centred at the vertices of a square . Find
the area of the central region bounded by the four arcs.
Draw two circles, each of radius 1 unit, so that each circle goes
through the centre of the other one. What is the area of the
What is the same and what is different about these circle
questions? What connections can you make?
A follow-up activity to Tiles in the Garden.
Analyse these beautiful biological images and attempt to rank them in size order.
Can you prove this formula for finding the area of a quadrilateral from its diagonals?
If I print this page which shape will require the more yellow ink?
The diagonals of a trapezium divide it into four parts. Can you
create a trapezium where three of those parts are equal in area?
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.
A square of area 40 square cms is inscribed in a semicircle. Find
the area of the square that could be inscribed in a circle of the
Prove that a triangle with sides of length 5, 5 and 6 has the same area as a triangle with sides of length 5, 5 and 8. Find other pairs of non-congruent isosceles triangles which 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.
Can you find the area of a parallelogram defined by two vectors?
This shape comprises four semi-circles. What is the relationship
between the area of the shaded region and the area of the circle on
AB as diameter?
A tower of squares is built inside a right angled isosceles
triangle. The largest square stands on the hypotenuse. What
fraction of the area of the triangle is covered by the series of
This article, written for teachers, discusses the merits of different kinds of resources: those which involve exploration and those which centre on calculation.
Bluey-green, white and transparent squares with a few odd bits of
shapes around the perimeter. But, how many squares are there of
each type in the complete circle? Study the picture and make. . . .
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!
Six circular discs are packed in different-shaped boxes so that the
discs touch their neighbours and the sides of the box. Can you put
the boxes in order according to the areas of their bases?
Can you maximise the area available to a grazing goat?
Imagine different shaped vessels being filled. Can you work out
what the graphs of the water level should look like?
Can you draw the height-time chart as this complicated vessel fills
A task which depends on members of the group noticing the needs of
others and responding.
Have a go at creating these images based on circles. What do you notice about the areas of the different sections?
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?
Derive a formula for finding the area of any kite.
How efficiently can you pack together disks?
Explore one of these five pictures.
An activity for high-attaining learners which involves making a new cylinder from a cardboard tube.
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?
I'm thinking of a rectangle with an area of 24. What could its perimeter be?
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?
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
Determine the total shaded area of the 'kissing triangles'.
Identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?
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?
Can you find rectangles where the value of the area is the same as the value of the perimeter?