A highly interactive Promethean ActivBoard flipchart where students discover the prime numbers, factors of numbers and the Highest Common Factor using a game based on Eratosthenes Sieve. Three thumbs up!

The flipchart can be found here:
http://www.prometheanplanet.com/uk/server/show/ConResource.13015

If you are not yet a member of Promethean Planet, you will first have to register here:
http://www.prometheanplanet.com/uk/server/show/nav.914

If you want to view the activities and have some interactivity with them, but you don't have the ActivStudio software, you can download the free Viewer from here:
http://www.mypromethean.com/uk/server/show/ConWebDoc.2974