Use the interactivity to sort these numbers into sets. Can you give each set a name?

Yasmin and Zach have some bears to share. Which numbers of bears can they share so that there are none left over?

Try to stop your opponent from being able to split the piles of counters into unequal numbers. Can you find a strategy?

This was a problem for our birthday website. Can you use four of these pieces to form a square? How about making a square with all five pieces?

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

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?

Use the interactivities to complete these Venn diagrams.

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?

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

Starting with the number 180, take away 9 again and again, joining up the dots as you go. Watch out - don't join all the dots!

Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?

Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.

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

Can you work out how to balance this equaliser? You can put more than one weight on a hook.

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?

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?

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?

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

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.

Sort the houses in my street into different groups. Can you do it in any other ways?

What are the coordinates of the coloured dots that mark out the tangram? Try changing the position of the origin. What happens to the coordinates now?

An interactive activity for one to experiment with a tricky tessellation

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. . . .

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

You have 4 red and 5 blue counters. How many ways can they be placed on a 3 by 3 grid so that all the rows columns and diagonals have an even number of red counters?

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

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

You'll need two dice to play this game against a partner. Will Incey Wincey make it to the top of the drain pipe or the bottom of the drain pipe first?

Mr Gilderdale is playing a game with his class. What rule might he have chosen? How would you test your idea?

Choose 13 spots on the grid. Can you work out the scoring system? What is the maximum possible score?

Create a pattern on the left-hand grid. How could you extend your pattern on the right-hand grid?

There are three versions of this challenge. The idea is to change the colour of all the spots on the grid. Can you do it in fewer throws of the dice?

A game for 1 person. Can you work out how the dice must be rolled from the start position to the finish? Play on line.

A game to be played against the computer, or in groups. Pick a 7-digit number. A random digit is generated. What must you subract to remove the digit from your number? the first to zero wins.

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

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.

Use the interactivity to help get a feel for this problem and to find out all the possible ways the balls could land.

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

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?

How many different rhythms can you make by putting two drums on the wheel?