### Traffic Lights

The game uses a 3x3 square board. 2 players take turns to play, either placing a red on an empty square, or changing a red to orange, or orange to green. The player who forms 3 of 1 colour in a line wins.

### Achi

This game for two players comes from Ghana. However, stones that were marked for this game in the third century AD have been found near Hadrian's Wall in Northern England.

### Yih or Luk Tsut K'i or Three Men's Morris

Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots and a little about prime knots, crossing numbers and knot arithmetic.

# Flip Flop - Matching Cards

##### Stage: 1, 2 and 3 Challenge Level:

Full Screen Version
This text is usually replaced by the Flash movie.

### HOW TO PLAY

The game begins with

16 cards face down. Alternatively you can choose the number of cards you want to play with.

The object of the game is to match pairs of numbers and number sentences, like pelmanism or pelmathism.

• Click on a card to flip it over. Repeat.
• If you select two cards which do not match up to make a pair, when you click again they will flip back over again, hiding the number or number sentence.
• Try to remember where the different numbers or number sentences are so that you can make a match.
• When the cards do match, you add 50 points to your starting score of 100. When they don't match, you lose 10 points.
• The game finishes when you have matched all the pairs.

### BE A WINNER

You play the game on the computer, but not against the computer. It is a game of skill, concentration and knowing your number bonds with an added element of chance.
Good number hunting and Good Luck!

### THE MATHS IS IN THE MATCHING

Where does the maths come in?
The numbers on the card are either a single number or a short number sentence such as 5+3. You have to match two cards that have the same total. Are some number bonds easier to remember than others? Find out which number bonds you need to get to know better.

### Printable Version

To download a printable version of this game use the links below. If you print double-sided, the cards will each have an NRICH logo on the back. If you would prefer them to be blank on the back, please just print the first page.