Another fraction manipulative I like is the Fraction Factory Kit from Creative Pursuits (I think that is the company).
One thing I find important is to have several favorite fraction manipulatives to use---other wise the kids seem to relate their understanding only to the shape, size, color etc. of the pieces I choose. For example, with this kit the unit is black, the 1/2 is orange, the 1/4 is purple. I often get stares implying my basic insanity (or something of that sort) if I ask them to consider the orange piece to be the unit and show me what should now be the 1/2!
Rosemary Beck Resource Math Teacher/Technology Coordinator Holaway Elementary School Tucson AZ email@example.com