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

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?

Watch this film carefully. Can you find a general rule for explaining when the dot will be this same distance from the horizontal axis?

In each of the pictures the invitation is for you to: Count what you see. Identify how you think the pattern would continue.

Nim-7 game for an adult and child. Who will be the one to take the last counter?

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

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.

Use your addition and subtraction skills, combined with some strategic thinking, to beat your partner at this game.

Here are some arrangements of circles. How many circles would I need to make the next size up for each? Can you create your own arrangement and investigate the number of circles it needs?

Can you find a way of counting the spheres in these arrangements?

These squares have been made from Cuisenaire rods. Can you describe the pattern? What would the next square look like?

This article for teachers describes several games, found on the site, all of which have a related structure that can be used to develop the skills of strategic planning.

Use the interactivity to investigate what kinds of triangles can be drawn on peg boards with different numbers of pegs.

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

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

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?

Think of a number, square it and subtract your starting number. Is the number youâ€™re left with odd or even? How do the images help to explain this?

Got It game for an adult and child. How can you play so that you know you will always win?

Can you work out how to win this game of Nim? Does it matter if you go first or second?

Can you dissect an equilateral triangle into 6 smaller ones? What number of smaller equilateral triangles is it NOT possible to dissect a larger equilateral triangle into?

Watch this animation. What do you see? Can you explain why this happens?

Take a counter and surround it by a ring of other counters that MUST touch two others. How many are needed?

Strike it Out game for an adult and child. Can you stop your partner from being able to go?

Two children made up a game as they walked along the garden paths. Can you find out their scores? Can you find some paths of your own?

Can you make dice stairs using the rules stated? How do you know you have all the possible stairs?

This challenge is about finding the difference between numbers which have the same tens digit.

Here are two kinds of spirals for you to explore. What do you notice?

Can you find all the ways to get 15 at the top of this triangle of numbers? Many opportunities to work in different ways.

The aim of the game is to slide the green square from the top right hand corner to the bottom left hand corner in the least number of moves.

Frances and Rishi were given a bag of lollies. They shared them out evenly and had one left over. How many lollies could there have been in the bag?

How many ways can you find to do up all four buttons on my coat? How about if I had five buttons? Six ...?

An article for teachers and pupils that encourages you to look at the mathematical properties of similar games.

How can you arrange these 10 matches in four piles so that when you move one match from three of the piles into the fourth, you end up with the same arrangement?

The NRICH team are always looking for new ways to engage teachers and pupils in problem solving. Here we explain the thinking behind maths trails.

Find out what a "fault-free" rectangle is and try to make some of your own.

Only one side of a two-slice toaster is working. What is the quickest way to toast both sides of three slices of bread?

This challenge asks you to imagine a snake coiling on itself.

A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

A game for 2 players with similarities to NIM. Place one counter on each spot on the games board. Players take it is turns to remove 1 or 2 adjacent counters. The winner picks up the last counter.

Find a route from the outside to the inside of this square, stepping on as many tiles as possible.

It starts quite simple but great opportunities for number discoveries and patterns!

Polygonal numbers are those that are arranged in shapes as they enlarge. Explore the polygonal numbers drawn here.

This activity involves rounding four-digit numbers to the nearest thousand.

This challenge encourages you to explore dividing a three-digit number by a single-digit number.

Are these statements relating to odd and even numbers always true, sometimes true or never true?

This task follows on from Build it Up and takes the ideas into three dimensions!

Florence, Ethan and Alma have each added together two 'next-door' numbers. What is the same about their answers?

Watch this video to see how to roll the dice. Now it's your turn! What do you notice about the dice numbers you have recorded?

Find the sum and difference between a pair of two-digit numbers. Now find the sum and difference between the sum and difference! What happens?