
Pumpkin patch

Seega

Alquerque

Introducing NRICH TWILGO


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

Clocking off

Prime magic


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.


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?

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

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

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

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.

Charting success

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.


Sprouts

Charting more success

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?


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.

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?

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

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?

Searching for mean(ing)

Sliding puzzle

What is the question?


Ding dong bell

Triangles in the middle

Fill me up too
In Fill Me Up we invited you to sketch graphs as vessels are filled with water. Can you work out the equations of the graphs?

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

Painted cube

Trisected triangle
Four tiles are given. For which of them can three be placed together to form an equilateral triangle?

Natural sum

Triangles within squares

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?

Plus minus

Making tracks



Tetrahedra tester

Quadratic patterns
Surprising numerical patterns can be explained using algebra and diagrams...

Triangles within pentagons


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?

One out one under


Pythagoras perimeters

Platonic planet


Vector walk


The perforated cube


The spider and the fly


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

Facial sums

Attractive tablecloths

All tied up


Cubic covering

Summing squares

Funnel
A plastic funnel is used to pour liquids through narrow apertures. What shape funnel would use the least amount of plastic to manufacture for any specific volume ?




Steel cables

Just rolling round

Out of the window

Around and back


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

Wari

Summing geometric progressions
Watch the video to see how to sum the sequence. Can you adapt the method to sum other sequences?

Coke machine



Triangle midpoints
You are only given the three midpoints of the sides of a triangle. How can you construct the original triangle?

Nicely similar
If the hypotenuse (base) length is 100cm and if an extra line splits the base into 36cm and 64cm parts, what were the side lengths for the original right-angled triangle?


Packing boxes

Just opposite

Bus stop


Doesn't add up
In this problem we are faced with an apparently easy area problem, but it has gone horribly wrong! What happened?

Dating made easier


Packing 3D shapes
What 3D shapes occur in nature. How efficiently can you pack these shapes together?