Wow, is this site ever COOL!
If you want some incredible on-line activities for your kids -OR- if you want to see how manipulatives can be used to increase mathematical understanding, go to the National Library of Virtual Manipulatives. You can access activities by grade band: PreK-2, 3-5, 6-8, and 9-12. Mathematical strands include: Number and Operations, Algebra, Geometry, Measurement, Data Analysis and Probability.
Here's a FABULOUS, FREE set of lessons that use the virtual spinners. Go to this page of The Math Learning Center website. Then look under "Data Analysis" for lesson set E1 Probability and Technology. This is a free pdf of fun lessons that go with the virtual spinners that are linked at the bottom of this page. Studetns use the virtual spinners to do two experiments before creating and testing their own spinners. The lessons are suitable for upper elementary students as they explore probability. FUN! (I showed the lessons/virtual spinners to a group of teachers last week...you should have heard the "Oohs and Ahhs." :)