List

Visualising - Upper Secondary

Introducing NRICH TWILGO
interactivity

Introducing NRICH TWILGO

We're excited about this new program for drawing beautiful mathematical designs. Can you work out how we made our first few pictures and, even better, share your most elegant solutions with us?
Baravelle
problem

Baravelle

Age
7 to 16
Challenge level
filled star filled star empty star
What can you see? What do you notice? What questions can you ask?
Prime Magic
problem

Prime Magic

Age
7 to 16
Challenge level
filled star filled star empty star
Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?
Cubic Conundrum
problem

Cubic Conundrum

Age
7 to 16
Challenge level
filled star filled star filled star
Which of the following cubes can be made from these nets?
Like a Circle in a Spiral
problem

Like a Circle in a Spiral

Age
7 to 16
Challenge level
filled star empty star empty star
A cheap and simple toy with lots of mathematics. Can you interpret the images that are produced? Can you predict the pattern that will be produced using different wheels?
Air Nets
problem

Air Nets

Age
7 to 18
Challenge level
filled star empty star empty star
Can you visualise whether these nets fold up into 3D shapes? Watch the videos each time to see if you were correct.
Clocking off
problem

Clocking off

Age
7 to 16
Challenge level
filled star empty star empty star
I found these clocks in the Arts Centre at the University of Warwick intriguing - do they really need four clocks and what times would be ambiguous with only two or three of them?
What is the question?
problem

What is the question?

Age
11 to 16
Challenge level
filled star empty star empty star
These pictures and answers leave the viewer with the problem "What is the Question". Can you give the question and how the answer follows?
Parallelogram It
problem

Parallelogram It

Age
11 to 16
Challenge level
filled star empty star empty star
Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a parallelogram.
The Bridges of Konigsberg
problem

The Bridges of Konigsberg

Age
11 to 18
Challenge level
filled star empty star empty star
Investigate how networks can be used to solve a problem for the 18th Century inhabitants of Konigsberg.
Semi-regular Tessellations
problem

Semi-regular Tessellations

Age
11 to 16
Challenge level
filled star empty star empty star
Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?
Rhombus It
problem

Rhombus It

Age
11 to 16
Challenge level
filled star filled star empty star
Players take it in turns to choose a dot on the grid. The winner is the first to have four dots that can be joined to form a rhombus.
Marbles in a box
problem

Marbles in a box

Age
11 to 16
Challenge level
filled star filled star empty star
How many winning lines can you make in a three-dimensional version of noughts and crosses?
Ding Dong Bell
article

Ding Dong Bell

The reader is invited to investigate changes (or permutations) in the ringing of church bells, illustrated by braid diagrams showing the order in which the bells are rung.
11x11 square
problem

11x11 square

Age
11 to 16
Challenge level
filled star filled star empty star
Here's a neat trick you can do with an 11 by 11 square...
Searching for mean(ing)
problem

Searching for mean(ing)

Age
11 to 16
Challenge level
filled star filled star empty star
If you have a large supply of 3kg and 8kg weights, how many of each would you need for the average (mean) of the weights to be 6kg?
Hamiltonian Cube
problem

Hamiltonian Cube

Age
11 to 16
Challenge level
filled star filled star empty star
Weekly Problem 36 - 2007
Find the length along the shortest path passing through certain points on the cube.
Multiple Surprises
problem

Multiple Surprises

Age
11 to 16
Challenge level
filled star empty star empty star
Sequences of multiples keep cropping up...
Shaping the universe I - planet Earth
article

Shaping the universe I - planet Earth

This article explores ths history of theories about the shape of our planet. It is the first in a series of articles looking at the significance of geometric shapes in the history of astronomy.
Funny Factorisation
problem

Funny Factorisation

Age
11 to 16
Challenge level
filled star filled star empty star
Using the digits 1 to 9, the number 4396 can be written as the product of two numbers. Can you find the factors?
Cuboid challenge
problem

Cuboid challenge

Age
11 to 16
Challenge level
filled star filled star empty star
What's the largest volume of box you can make from a square of paper?
LOGO Challenge - Triangles-Squares-Stars
problem

LOGO Challenge - Triangles-Squares-Stars

Age
11 to 16
Challenge level
filled star filled star empty star
Can you recreate these designs? What are the basic units? What movement is required between each unit? Some elegant use of procedures will help - variables not essential.
Charting success
problem

Charting success

Age
11 to 16
Challenge level
filled star empty star empty star
Can you make sense of the charts and diagrams that are created and used by sports competitors, trainers and statisticians?
Instant Insanity
problem

Instant Insanity

Age
11 to 18
Challenge level
filled star filled star filled star
Given the nets of 4 cubes with the faces coloured in 4 colours, build a tower so that on each vertical wall no colour is repeated, that is all 4 colours appear.
Nine Colours
problem

Nine Colours

Age
11 to 16
Challenge level
filled star filled star filled star
Can you use small coloured cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of each colour?
Placeholder: several colourful numbers
problem

Triangles in the middle

Age
11 to 18
Challenge level
filled star empty star empty star
This task depends on groups working collaboratively, discussing and reasoning to agree a final product.
Charting more success
problem

Charting more success

Age
11 to 16
Challenge level
filled star empty star empty star
Can you make sense of the charts and diagrams that are created and used by sports competitors, trainers and statisticians?
Twelve Cubed
problem

Twelve Cubed

Age
14 to 16
Challenge level
filled star empty star empty star
A wooden cube with edges of length 12cm is cut into cubes with edges of length 1cm. What is the total length of the all the edges of these centimetre cubes?
Semicircular Design
problem

Semicircular Design

Age
14 to 16
Challenge level
filled star empty star empty star
Weekly Problem 9 - 2016
The diagram to the right shows a logo made from semi-circular arcs. What fraction of the logo is shaded?
AMGM
problem

AMGM

Age
14 to 16
Challenge level
filled star filled star filled star
Can you use the diagram to prove the AM-GM inequality?
Corridors
problem

Corridors

Age
14 to 16
Challenge level
filled star filled star empty star
A 10x10x10 cube is made from 27 2x2 cubes with corridors between them. Find the shortest route from one corner to the opposite corner.
Facial Sums
problem

Facial Sums

Age
14 to 16
Challenge level
filled star filled star empty star
Can you make the numbers around each face of this solid add up to the same total?
Just rolling round
problem

Just rolling round

Age
14 to 16
Challenge level
filled star filled star filled star
P is a point on the circumference of a circle radius r which rolls, without slipping, inside a circle of radius 2r. What is the locus of P?
3D Treasure Hunt
problem

3D Treasure Hunt

Age
14 to 18
Challenge level
filled star filled star empty star
Some treasure has been hidden in a three-dimensional grid! Can you work out a strategy to find it as efficiently as possible?
Steel Cables
problem

Steel Cables

Age
14 to 16
Challenge level
filled star empty star empty star
Some students have been working out the number of strands needed for different sizes of cable. Can you make sense of their solutions?
Doesn't add up
problem

Doesn't add up

Age
14 to 16
Challenge level
filled star filled star empty star

In this problem we are faced with an apparently easy area problem, but it has gone horribly wrong! What happened?

Dicey Directions
problem

Dicey Directions

Age
14 to 16
Challenge level
filled star empty star empty star
An ordinary die is placed on a horizontal table with the '1' face facing East... In which direction is the '1' face facing after this sequence of moves?
Travelling by Train
problem

Travelling by Train

Age
14 to 16
Challenge level
filled star filled star empty star
Stephen stops at Darlington on his way to Durham. At what time does he arrive at Durham?
Gnomon dimensions
problem

Gnomon dimensions

Age
14 to 16
Challenge level
filled star filled star empty star
These gnomons appear to have more than a passing connection with the Fibonacci sequence. This problem ask you to investigate some of these connections.
Speeding boats
problem

Speeding boats

Age
14 to 16
Challenge level
filled star empty star empty star
Two boats travel up and down a lake. Can you picture where they will cross if you know how fast each boat is travelling?
Always Perfect
problem

Always Perfect

Age
14 to 18
Challenge level
filled star filled star empty star
Show that if you add 1 to the product of four consecutive numbers the answer is ALWAYS a perfect square.
Centre Square
problem

Centre Square

Age
14 to 16
Challenge level
filled star filled star filled star
What does Pythagoras' Theorem tell you about the radius of these circles?
Coke machine
problem

Coke machine

Age
14 to 16
Challenge level
filled star empty star empty star
The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design...
Slippage
problem

Slippage

Age
14 to 16
Challenge level
filled star filled star empty star
A ladder 3m long rests against a wall with one end a short distance from its base. Between the wall and the base of a ladder is a garden storage box 1m tall and 1m high. What is the maximum distance up the wall which the ladder can reach?
Fermat's Poser
problem

Fermat's Poser

Age
14 to 16
Challenge level
filled star filled star filled star
Find the point whose sum of distances from the vertices (corners) of a given triangle is a minimum.
Spotting the loophole
problem

Spotting the loophole

Age
14 to 16
Challenge level
filled star empty star empty star
A visualisation problem in which you search for vectors which sum to zero from a jumble of arrows. Will your eyes be quicker than algebra?
Oldest and Youngest
problem

Oldest and Youngest

Age
14 to 16
Challenge level
filled star filled star empty star
Edith had 9 children at 15 month intervals. If the oldest is now six times as old as the youngest, how old is her youngest child?
Iff
problem

Iff

Age
14 to 18
Challenge level
filled star filled star empty star
Take a triangular number, multiply it by 8 and add 1. What is special about your answer? Can you prove it?
Back fitter
problem

Back fitter

Age
14 to 18
Challenge level
filled star filled star empty star

10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?

Perfectly Square
problem

Perfectly Square

Age
14 to 16
Challenge level
filled star filled star empty star
The sums of the squares of three related numbers is also a perfect square - can you explain why?
Folding in Half
problem

Folding in Half

Age
14 to 16
Challenge level
filled star filled star empty star
How does the perimeter change when we fold this isosceles triangle in half?
Just Opposite
problem

Just Opposite

Age
14 to 16
Challenge level
filled star filled star empty star
A and C are the opposite vertices of a square ABCD, and have coordinates (a,b) and (c,d), respectively. What are the coordinates of the vertices B and D? What is the area of the square?
Double Trouble
problem

Double Trouble

Age
14 to 16
Challenge level
filled star empty star empty star
Simple additions can lead to intriguing results...
A Problem of time
problem

A Problem of time

Age
14 to 16
Challenge level
filled star filled star filled star
Consider a watch face which has identical hands and identical marks for the hours. It is opposite to a mirror. When is the time as read direct and in the mirror exactly the same between 6 and 7?
Making Tracks
problem

Making Tracks

Age
14 to 16
Challenge level
filled star filled star empty star
A bicycle passes along a path and leaves some tracks. Is it possible to say which track was made by the front wheel and which by the back wheel?
Travelator
problem

Travelator

Age
14 to 16
Challenge level
filled star filled star empty star
When Andrew arrives at the end of the walkway, how far is he ahead of Bill?
Tetra Square
problem

Tetra Square

Age
14 to 18
Challenge level
filled star filled star empty star
ABCD is a regular tetrahedron and the points P, Q, R and S are the midpoints of the edges AB, BD, CD and CA. Prove that PQRS is a square.
Changing Places
problem

Changing Places

Age
14 to 16
Challenge level
filled star empty star empty star
Place a red counter in the top left corner of a 4x4 array, which is covered by 14 other smaller counters, leaving a gap in the bottom right hand corner (HOME). What is the smallest number of moves it will take to move the red counter to HOME?
Packing Boxes
problem

Packing Boxes

Age
14 to 16
Challenge level
filled star filled star empty star
Look at the times that Harry, Christine and Betty take to pack boxes when working in pairs, to find how fast Christine can pack boxes by herself.
Building Tetrahedra
problem

Building Tetrahedra

Age
14 to 16
Challenge level
filled star filled star empty star
Can you make a tetrahedron whose faces all have the same perimeter?
Triangles within Triangles
problem

Triangles within Triangles

Age
14 to 16
Challenge level
filled star empty star empty star
Can you find a rule which connects consecutive triangular numbers?
Hypotenuse Lattice points
problem

Hypotenuse Lattice points

Age
14 to 16
Challenge level
filled star filled star filled star
The triangle OMN has vertices on the axes with whole number co-ordinates. How many points with whole number coordinates are there on the hypotenuse MN?
One Out One Under
problem

One Out One Under

Age
14 to 16
Challenge level
filled star filled star filled star
Imagine a stack of numbered cards with one on top. Discard the top, put the next card to the bottom and repeat continuously. Can you predict the last card?
Tennis Training
problem

Tennis Training

Age
14 to 16
Challenge level
filled star filled star empty star
After tennis training, Andy, Roger and Maria collect up the balls. Can you work out how many Andy collects?
Concrete calculation
problem

Concrete calculation

Age
14 to 16
Challenge level
filled star filled star empty star
The builders have dug a hole in the ground to be filled with concrete for the foundations of our garage. How many cubic metres of ready-mix concrete should the builders order to fill this hole to make the concrete raft for the foundations?
Surprising Transformations
problem

Surprising Transformations

Age
14 to 16
Challenge level
filled star filled star empty star

I took the graph y=4x+7 and performed four transformations. Can you find the order in which I could have carried out the transformations?

Painted Cube
problem

Painted Cube

Age
14 to 16
Challenge level
filled star filled star empty star
Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?
Newspaper Sheets
problem

Newspaper Sheets

Age
14 to 16
Challenge level
filled star filled star empty star
From only the page numbers on one sheet of newspaper, can you work out how many sheets there are altogether?
Triangles within Squares
problem

Triangles within Squares

Age
14 to 16
Challenge level
filled star filled star empty star
Can you find a rule which relates triangular numbers to square numbers?
Triangles within Pentagons
problem

Triangles within Pentagons

Age
14 to 16
Challenge level
filled star filled star filled star
Show that all pentagonal numbers are one third of a triangular number.
Relative Time
problem

Relative Time

Age
14 to 16
Challenge level
filled star filled star empty star
Albert Einstein is experimenting with two unusual clocks. At what time do they next agree?
Star Gazing
problem

Star Gazing

Age
14 to 16
Challenge level
filled star empty star empty star
Find the ratio of the outer shaded area to the inner area for a six pointed star and an eight pointed star.
The perforated cube
problem

The perforated cube

Age
14 to 16
Challenge level
filled star empty star empty star
A cube is made from smaller cubes, 5 by 5 by 5, then some of those cubes are removed. Can you make the specified shapes, and what is the most and least number of cubes required ?
Vanishing point
problem

Vanishing point

Age
14 to 18
Challenge level
filled star filled star empty star
How can visual patterns be used to prove sums of series?
Vector walk
problem

Vector walk

Age
14 to 18
Challenge level
filled star empty star empty star
Starting with two basic vector steps, which destinations can you reach on a vector walk?
Tetrahedra Tester
problem

Tetrahedra Tester

Age
14 to 16
Challenge level
filled star filled star empty star
An irregular tetrahedron is composed of four different triangles. Can such a tetrahedron be constructed where the side lengths are 4, 5, 6, 7, 8 and 9 units of length?
Mixing More Paints
problem

Mixing More Paints

Age
14 to 16
Challenge level
filled star filled star filled star
Can you find an efficent way to mix paints in any ratio?
Eulerian
problem

Eulerian

Age
14 to 16
Challenge level
filled star empty star empty star
Weekly Problem 37 - 2014
Which of the five diagrams below could be drawn without taking the pen off the page and without drawing along a line already drawn?
Penta Colour
problem

Penta Colour

Age
14 to 16
Challenge level
filled star empty star empty star
In how many different ways can I colour the five edges of a pentagon so that no two adjacent edges are the same colour?
Negatively Triangular
problem

Negatively Triangular

Age
14 to 16
Challenge level
filled star filled star empty star

How many intersections do you expect from four straight lines ? Which three lines enclose a triangle with negative co-ordinates for every point ?

Tilting Triangles
problem

Tilting Triangles

Age
14 to 16
Challenge level
filled star filled star empty star
A right-angled isosceles triangle is rotated about the centre point of a square. What can you say about the area of the part of the square covered by the triangle as it rotates?
Which is cheaper?
problem

Which is cheaper?

Age
14 to 16
Challenge level
filled star empty star empty star
When I park my car in Mathstown, there are two car parks to choose from. Can you help me to decide which one to use?
Bendy Quad
problem

Bendy Quad

Age
14 to 16
Challenge level
filled star filled star filled star
Four rods are hinged at their ends to form a convex quadrilateral. Investigate the different shapes that the quadrilateral can take. Be patient this problem may be slow to load.
Pyramidal n-gon
problem

Pyramidal n-gon

Age
14 to 16
Challenge level
filled star filled star empty star
The base of a pyramid has n edges. What is the difference between the number of edges the pyramid has and the number of faces the pyramid has?
Escalator
problem

Escalator

Age
14 to 16
Challenge level
filled star filled star empty star
At Holborn underground station there is a very long escalator. Two people are in a hurry and so climb the escalator as it is moving upwards, thus adding their speed to that of the moving steps. ... How many steps are there on the escalator?
A Tilted Square
problem

A Tilted Square

Age
14 to 16
Challenge level
filled star filled star filled star
The opposite vertices of a square have coordinates (a,b) and (c,d). What are the coordinates of the other vertices?
Summing squares
problem

Summing squares

Age
14 to 16
Challenge level
filled star filled star empty star
Discover a way to sum square numbers by building cuboids from small cubes. Can you picture how the sequence will grow?
The Spider and the Fly
problem

The Spider and the Fly

Age
14 to 16
Challenge level
filled star filled star empty star
A spider is sitting in the middle of one of the smallest walls in a room and a fly is resting beside the window. What is the shortest distance the spider would have to crawl to catch the fly?
Which is bigger?
problem

Which is bigger?

Age
14 to 16
Challenge level
filled star filled star empty star
Which is bigger, n+10 or 2n+3? Can you find a good method of answering similar questions?
Contact
problem

Contact

Age
14 to 16
Challenge level
filled star filled star empty star
A circular plate rolls in contact with the sides of a rectangular tray. How much of its circumference comes into contact with the sides of the tray when it rolls around one circuit?
In or Out?
problem

In or Out?

Age
14 to 16
Challenge level
filled star filled star filled star
Weekly Problem 52 - 2014
Four arcs are drawn in a circle to create a shaded area. What fraction of the area of the circle is shaded?
Tied up
problem

Tied up

Age
14 to 16
Challenge level
filled star filled star empty star
How much of the field can the animals graze?
Efficient packing
problem

Efficient packing

Age
14 to 16
Challenge level
filled star empty star empty star
How efficiently can you pack together disks?
All Tied Up
problem

All Tied Up

Age
14 to 16
Challenge level
filled star filled star empty star
A ribbon runs around a box so that it makes a complete loop with two parallel pieces of ribbon on the top. How long will the ribbon be?
Picture Story
problem

Picture Story

Age
14 to 16
Challenge level
filled star filled star empty star
Can you see how this picture illustrates the formula for the sum of the first six cube numbers?
Cubic Covering
problem

Cubic Covering

Age
14 to 16
Challenge level
filled star filled star empty star
A blue cube has blue cubes glued on all of its faces. Yellow cubes are then glued onto all the visible blue facces. How many yellow cubes are needed?