
Pumpkin patch

Seega

Alquerque

Introducing NRICH TWILGO

Clocking off


Fruity totals
In this interactivity each fruit has a hidden value. Can you deduce what each one is worth?

Like a circle in a spiral

Air nets

Prime magic

Triangle in a trapezium
Can you find and prove the relationship between the area of a trapezium and the area of a triangle constructed within it?

What is the question?

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.

Yih or Luk tsut k'i or Three Men's Morris
Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots and a little about prime knots, crossing numbers and knot arithmetic.

Marbles in a box
How many winning lines can you make in a three-dimensional version of noughts and crosses?

Triangles in the middle

Shaping the universe II - the solar system
The second in a series of articles on visualising and modelling shapes in the history of astronomy.

Sprouts

Shaping the universe III - to infinity and beyond
The third installment in our series on the shape of astronomical systems, this article explores galaxies and the universe beyond our solar system.

The bridges of Konigsberg
Investigate how networks can be used to solve a problem for the 18th Century inhabitants of Konigsberg.

Instant insanity
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.

Funny factorisation

What's it worth?
There are lots of different methods to find out what the shapes are worth - how many can you find?

Charlie's delightful machine
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?




LOGO challenge - circles as animals
See if you can anticipate successive 'generations' of the two animals shown here.

Nine colours

LOGO challenge - triangles-squares-stars
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


Take three from five
Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?

Charting more success

Searching for mean(ing)

Sliding puzzle




Hamiltonian cube
Find the length along the shortest path passing through certain points on the cube.

Ding dong bell

Painted purple

Pair products
Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?

Which is bigger?

Picture story

3D treasure hunt
Some treasure has been hidden in a three-dimensional grid! Can you work out a strategy to find it as efficiently as possible?


Curvy areas
Have a go at creating these images based on circles. What do you notice about the areas of the different sections?

Isosceles seven
Is it possible to find the angles in this rather special isosceles triangle?

Tilting triangles

Partly painted cube


Perfectly square

Track design
Where should runners start the 200m race so that they have all run the same distance by the finish?

Proximity

Slippage

One and three

Building gnomons

A tilted square

When the angles of a triangle don't add up to 180 degrees

Changing places

Natural sum

Kite in a square
Can you make sense of the three methods to work out what fraction of the total area is shaded?

Plus minus

Twelve cubed

Semicircular design
The diagram to the right shows a logo made from semi-circular arcs. What fraction of the logo is shaded?


Painted cube


Triangles within triangles

Relative time

Sitting pretty
A circle of radius r touches two sides of a right angled triangle, sides x and y, and has its centre on the hypotenuse. Can you prove the formula linking x, y and r?

Dicey directions

Speeding boats

Travelling by train

Tetrahedra tester


Platonic planet

Triangles within squares

Eulerian
Which of the five diagrams below could be drawn without taking the pen off the page and without drawing along a line already drawn?

Spotting the loophole
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

Vector journeys
Charlie likes to go for walks around a square park, while Alison likes to cut across diagonally. Can you find relationships between the vectors they walk along?


Triangles within pentagons

Pyramidal n-gon

Making tracks

Back fitter
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?



Attractive tablecloths


The spider and the fly

Factorising with multilink


In or out?
Four arcs are drawn in a circle to create a shaded area. What fraction of the area of the circle is shaded?

One out one under

Surprising transformations
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?

Tennis training

Jam
To avoid losing think of another very well known game where the patterns of play are similar.