Arrange any number of counters from these 18 on the grid to make a rectangle. What numbers of counters make rectangles? How many different rectangles can you make with each number of counters?

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?

A game for 2 people that everybody knows. You can play with a friend or online. If you play correctly you never lose!

Move just three of the circles so that the triangle faces in the opposite direction.

An interactive game for 1 person. You are given a rectangle with 50 squares on it. Roll the dice to get a percentage between 2 and 100. How many squares is this? Keep going until you get 100. . . .

A game for 2 people that can be played on line or with pens and paper. Combine your knowledege of coordinates with your skills of strategic thinking.

Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?

An interactive game to be played on your own or with friends. Imagine you are having a party. Each person takes it in turns to stand behind the chair where they will get the most chocolate.

Take it in turns to make a triangle on the pegboard. Can you block your opponent?

Use the interactivity to find out how many quarter turns the man must rotate through to look like each of the pictures.

Play this well-known game against the computer where each player is equally likely to choose scissors, paper or rock. Why not try the variations too?

What does the overlap of these two shapes look like? Try picturing it in your head and then use the interactivity to test your prediction.

Can you hang weights in the right place to make the equaliser balance?

If you can post the triangle with either the blue or yellow colour face up, how many ways can it be posted altogether?

Take it in turns to place a domino on the grid. One to be placed horizontally and the other vertically. Can you make it impossible for your opponent to play?

Can you sort these triangles into three different families and explain how you did it?

Our 2008 Advent Calendar has a 'Making Maths' activity for every day in the run-up to Christmas.

In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?

Train game for an adult and child. Who will be the first to make the train?

Stop the Clock game for an adult and child. How can you make sure you always win this game?

Incey Wincey Spider game for an adult and child. Will Incey get to the top of the drainpipe?

Complete the squares - but be warned some are trickier than they look!

Work out the fractions to match the cards with the same amount of money.

Use the interactivities to fill in these Carroll diagrams. How do you know where to place the numbers?

If there are 3 squares in the ring, can you place three different numbers in them so that their differences are odd? Try with different numbers of squares around the ring. What do you notice?

Ahmed has some wooden planks to use for three sides of a rabbit run against the shed. What quadrilaterals would he be able to make with the planks of different lengths?

Use the number weights to find different ways of balancing the equaliser.

NRICH December 2006 advent calendar - a new tangram for each day in the run-up to Christmas.

This is a game for two players. Can you find out how to be the first to get to 12 o'clock?

Can you fit the tangram pieces into the outlines of the lobster, yacht and cyclist?

Can you fit the tangram pieces into the outlines of the chairs?

A shape and space game for 2,3 or 4 players. Be the last person to be able to place a pentomino piece on the playing board. Play with card, or on the computer.

Can you fit the tangram pieces into the outline of the child walking home from school?

Can you fit the tangram pieces into the outline of this brazier for roasting chestnuts?

Hover your mouse over the counters to see which ones will be removed. Click to remover them. The winner is the last one to remove a counter. How you can make sure you win?

Can you fit the tangram pieces into the outline of this telephone?

Can you fit the tangram pieces into the outline of Little Fung at the table?

Can you fit the tangram pieces into the outlines of these clocks?

A game for 1 or 2 people. Use the interactive version, or play with friends. Try to round up as many counters as possible.

Can you fit the tangram pieces into the outlines of the workmen?

Exchange the positions of the two sets of counters in the least possible number of moves