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?

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?

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

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

What happens when you try and fit the triomino pieces into these two grids?

Use your mouse to move the red and green parts of this disc. Can you make images which show the turnings described?

Find out how we can describe the "symmetries" of this triangle and investigate some combinations of rotating and flipping it.

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?

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?

Three beads are threaded on a circular wire and are coloured either red or blue. Can you find all four different combinations?

Cut four triangles from a square as shown in the picture. How many different shapes can you make by fitting the four triangles back together?

An interactive activity for one to experiment with a tricky tessellation

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

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

Board Block game for two. Can you stop your partner from being able to make a shape on the board?

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

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.

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

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

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 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.

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

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?

How have the numbers been placed in this Carroll diagram? Which labels would you put on each row and column?

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

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

How many different triangles can you make on a circular pegboard that has nine pegs?

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

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

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

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

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

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

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

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

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?

Explore the different tunes you can make with these five gourds. What are the similarities and differences between the two tunes you are given?

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

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

Place the numbers 1 to 10 in the circles so that each number is the difference between the two numbers just below it.

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