Choose four of the numbers from 1 to 9 to put in the squares so that the differences between joined squares are odd.

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

Use the information about Sally and her brother to find out how many children there are in the Brown family.

Ben and his mum are planting garlic. Use the interactivity to help you find out how many cloves of garlic they might have had.

How many different triangles can you draw on the dotty grid which each have one dot in the middle?

Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

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!

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

How many different ways can you find to join three equilateral triangles together? Can you convince us that you have found them all?

Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?

An environment which simulates working with Cuisenaire rods.

Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?

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

Here is a chance to play a version of the classic Countdown Game.

This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?

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

Can you use the numbers on the dice to reach your end of the number line before your partner beats you?

What do the numbers shaded in blue on this hundred square have in common? What do you notice about the pink numbers? How about the shaded numbers in the other squares?

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

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

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?

Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

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

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

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

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

This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.

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

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?

Can you make a train the same length as Laura's but using three differently coloured rods? Is there only one way of doing it?

An interactive activity for one to experiment with a tricky tessellation

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

In your bank, you have three types of coins. The number of spots shows how much they are worth. Can you choose coins to exchange with the groups given to make the same total?

Place six toy ladybirds into the box so that there are two ladybirds in every column and every row.

This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?

Can you make the green spot travel through the tube by moving the yellow spot? Could you draw a tube that both spots would follow?

Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?