This article explains how tree diagrams are constructed and helps you to understand how they can be used to calculate probabilities.

What do we mean by probability? This simple problem may challenge your ideas...

A gambler bets half the money in his pocket on the toss of a coin, winning an equal amount for a head and losing his money if the result is a tail. After 2n plays he has won exactly n times. Has. . . .

Think that a coin toss is 50-50 heads or tails? Read on to appreciate the ever-changing and random nature of the world in which we live.

Some people offer advice on how to win at games of chance, or how to influence probability in your favour. Can you decide whether advice is good or not?

What are the likelihoods of different events when you roll a dice?

When five dice are rolled together which do you expect to see more often, no sixes or all sixes ?

Which of these ideas about randomness are actually correct?

Can you design your own probability scale?

How do you describe the different parts?

Chris and Jo put two red and four blue ribbons in a box. They each pick a ribbon from the box without looking. Jo wins if the two ribbons are the same colour. Is the game fair?

Four fair dice are marked differently on their six faces. Choose first ANY one of them. I can always choose another that will give me a better chance of winning. Investigate.

Is a score of 9 more likely than a score of 10 when you roll three dice?

If two of these unusually numbered dice are thrown, how many different sums are possible?

Can you generate a set of random results? Can you fool the random simulator?

Can you work out which spinners were used to generate the frequency charts?

The King showed the Princess a map of the maze and the Princess was allowed to decide which room she would wait in. She was not allowed to send a copy to her lover who would have to guess which path. . . .

Explore the distribution of molecular masses for various hydrocarbons

Alison and Charlie are playing a game. Charlie wants to go first so Alison lets him. Was that such a good idea?

Uncertain about the likelihood of unexpected events? You are not alone!

If a coin rolls and lands on a set of concentric circles what is the chance that the coin touches a line ?

In a race the odds are: 2 to 1 against the rhinoceros winning and 3 to 2 against the hippopotamus winning. What are the odds against the elephant winning if the race is fair?

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

You have two bags, four red balls and four white balls. You must put all the balls in the bags although you are allowed to have one bag empty. How should you distribute the balls between the two. . . .

The four digits 5, 6, 7 and 8 are put at random in the spaces of the number : 3 _ 1 _ 4 _ 0 _ 9 2 Calculate the probability that the answer will be a multiple of 396.

To win on a scratch card you have to uncover three numbers that add up to more than fifteen. What is the probability of winning a prize?

A simple spinner that is equally likely to land on Red or Black. Useful if tossing a coin, dropping it, and rummaging about on the floor have lost their appeal. Needs a modern browser; if IE then at. . . .

Under which circumstances would you choose to play to 10 points in a game of squash which is currently tied at 8-all?

Can you beat Piggy in this simple dice game? Can you figure out Piggy's strategy, and is there a better one?

Use trigonometry to determine whether solar eclipses on earth can be perfect.

Here are some examples of 'cons', and see if you can figure out where the trick is.

All you need for this game is a pack of cards. While you play the game, think about strategies that will increase your chances of winning.

In the time before the mathematical idea of randomness was discovered, people thought that everything that happened was part of the will of supernatural beings. So have things changed?

Fancy a game of cricket? Here is a mathematical version you can play indoors without breaking any windows.