Poisson Rouge - a wonderful site!
Prepare to spend a long time on this site. Adults and children alike find it fascinating. Some activities work really well on an Interactive Whiteboard, particularly the number blocks. Numbers 7 and 8 are my favourites.
The alphabets are great too, the second giving some French vocabulary :-)
Poisson Rouge

Don't forget to press F11 to take off the address bar and run 'full screen'. F11 toggles it back again too.