To protect themselves from Hacker's constant attempts to capture cybersite Happily-Ever-After, the King and his fairy-tale subjects construct a glass Skywall to keep Hacker out of the kingdom. But Hacker unfolds a brilliant scheme to crack open the Skywall - using the Wicked Witch's Voice! Can the kids use models to outwit Hacker before Wicked sings?!! The Big Idea: Make a model - a simplified version of something complicated - and you can easily and safely understand how it works. Math Topic: Using Models NCTM Links: Geometry.