You will need:
2 dice and a pen and paper.
Take in turns to:
 Throw the dice
 From the dice, construct 2 or perhaps 3 numbers. For example, if you throw a two and a three, you can make 5, 23 and 32 (3+2=5, two followed by three is 23 and three followed by two is 32)
 Score one point for each prime number you have made (so this example scores one for the 5 and one for the 23, scoring two points in total).
 If you need to use a calculator, then a Casio fx83GT PLUS can tell you whether a number is prime. This is *not* cheating – students will soon start to recognise the primes they need, rather than having to check using the calculator!
The Winner Is:
The person who has the most points.
Things to discuss:
 Why are two even numbers always such bad news? (even+even=even and the only even prime number is two)
 Is it possible to score three points with one throw?
 If there is a six in your throw, what happens?
This sample space diagram may help:
Sample Space Diagram for 2 Dice 

1 
2 
3 
4 
5 
6 

1 
(1,1) 
(2,1) 
(3,1) 
(4,1) 
(5,1) 
(6,1) 
2 
(1,2) 
(2,2) 
(3,2) 
(4,2) 
(5,2) 
(6,2) 
3 
(1,3) 
(2,3) 
(3,3) 
(4,3) 
(5,3) 
(6,3) 
4 
(1,4) 
(2,4) 
(3,4) 
(4,4) 
(5,4) 
(6,4) 
5 
(1,5) 
(2,5) 
(3,5) 
(4,5) 
(5,5) 
(6,5) 
6 
(1,6) 
(2,6) 
(3,6) 
(4,6) 
(5,6) 
(6,6) 