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?

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

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

Use the interactivities to complete these Venn diagrams.

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!

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

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

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

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?

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

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. . . .

An interactive activity for one to experiment with a tricky tessellation

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?

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?

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.

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

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

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

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

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?

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?

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?

Use the interactivity to create some steady rhythms. How could you create a rhythm which sounds the same forwards as it does backwards?

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

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?

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

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?

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

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?

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

Can you work out what is wrong with the cogs on a UK 2 pound coin?

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?

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?

Use the Cuisenaire rods environment to investigate ratio. Can you find pairs of rods in the ratio 3:2? How about 9:6?

If you have only four weights, where could you place them in order to balance this equaliser?

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

How many times in twelve hours do the hands of a clock form a right angle? Use the interactivity to check your answers.

How many trains can you make which are the same length as Matt's, using rods that are identical?

Choose the size of your pegboard and the shapes you can make. Can you work out the strategies needed to block your opponent?

A tetromino is made up of four squares joined edge to edge. Can this tetromino, together with 15 copies of itself, be used to cover an eight by eight chessboard?

Use the interactivity or play this dice game yourself. How could you make it fair?