Try entering different sets of numbers in the number pyramids. How does the total at the top change?

Meg and Mo need to hang their marbles so that they balance. Use the interactivity to experiment and find out what they need to do.

When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...

The number of plants in Mr McGregor's magic potting shed increases overnight. He'd like to put the same number of plants in each of his gardens, planting one garden each day. How can he do it?

Triangular numbers can be represented by a triangular array of squares. What do you notice about the sum of identical triangle numbers?

Can you explain the strategy for winning this game with any target?

Six balls of various colours are randomly shaken into a trianglular arrangement. What is the probability of having at least one red in the corner?

Meg and Mo still need to hang their marbles so that they balance, but this time the constraints are different. Use the interactivity to experiment and find out what they need to do.

Mo has left, but Meg is still experimenting. Use the interactivity to help you find out how she can alter her pouch of marbles and still keep the two pouches balanced.

This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.

Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?

A and B are two interlocking cogwheels having p teeth and q teeth respectively. One tooth on B is painted red. Find the values of p and q for which the red tooth on B contacts every gap on the. . . .

Can you make a right-angled triangle on this peg-board by joining up three points round the edge?

Here is a chance to play a version of the classic Countdown Game.

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?

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. . . .

Can you find a reliable strategy for choosing coordinates that will locate the treasure in the minimum number of guesses?

Mr McGregor has a magic potting shed. Overnight, the number of plants in it doubles. He'd like to put the same number of plants in each of three gardens, planting one garden each day. Can he do it?

A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

Can you spot the similarities between this game and other games you know? The aim is to choose 3 numbers that total 15.

7 balls are shaken in a container. You win if the two blue balls touch. What is the probability of winning?

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

We can show that (x + 1)² = x² + 2x + 1 by considering the area of an (x + 1) by (x + 1) square. Show in a similar way that (x + 2)² = x² + 4x + 4

The aim of the game is to slide the green square from the top right hand corner to the bottom left hand corner in the least number of moves.

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. . . .

A tilted square is a square with no horizontal sides. Can you devise a general instruction for the construction of a square when you are given just one of its sides?

It's easy to work out the areas of most squares that we meet, but what if they were tilted?

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 square.

There are nine teddies in Teddy Town - three red, three blue and three yellow. There are also nine houses, three of each colour. Can you put them on the map of Teddy Town according to the rules?

This problem is about investigating whether it is possible to start at one vertex of a platonic solid and visit every other vertex once only returning to the vertex you started at.

Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

Two engines, at opposite ends of a single track railway line, set off towards one another just as a fly, sitting on the front of one of the engines, sets off flying along the railway line...

The opposite vertices of a square have coordinates (a,b) and (c,d). What are the coordinates of the other vertices?

Can you put the 25 coloured tiles into the 5 x 5 square so that no column, no row and no diagonal line have tiles of the same colour in them?

Two circles of equal radius touch at P. One circle is fixed whilst the other moves, rolling without slipping, all the way round. How many times does the moving coin revolve before returning to P?

Euler discussed whether or not it was possible to stroll around Koenigsberg crossing each of its seven bridges exactly once. Experiment with different numbers of islands and bridges.

Find the frequency distribution for ordinary English, and use it to help you crack the code.

Semi-regular tessellations combine two or more different regular polygons to fill the plane. Can you find all the semi-regular tessellations?

An activity based on the game 'Pelmanism'. Set your own level of challenge and beat your own previous best score.

A game in which players take it in turns to choose a number. Can you block your opponent?

This interactivity invites you to make conjectures and explore probabilities of outcomes related to two independent events.

Can you find triangles on a 9-point circle? Can you work out their angles?

Show how this pentagonal tile can be used to tile the plane and describe the transformations which map this pentagon to its images in the tiling.

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?

Identical discs are flipped in the air. You win if all of the faces show the same colour. Can you calculate the probability of winning with n discs?

Add or subtract the two numbers on the spinners and try to complete a row of three. Are there some numbers that are good to aim for?

The computer has made a rectangle and will tell you the number of spots it uses in total. Can you find out where the rectangle is?