The Leaders of Cyberspace have gathered to discuss Hacker's increasing influence, when they are suddenly interrupted by Hacker. Buzz and Delete, Hacker's henchmen, hide the leaders including Dr. Marbles, in the building and its' up to the kids to rescue them. Before long, the kids discover that they can only move between the building's levels by scaling its outside walls! So the kids turn the building into a giant ruler in order to keep track of the floors. And when they discover that there are levels beneath what they thought was "zero," the kids must tap into the power of negative numbers. The Big Idea: Numbers don't have to stop at zero! Negative numbers -- numbers that are less than zero -- can extend the range of what you can measure on a scale and give you the ability to compare numbers using direction as well as amount. Math Topic: Negative Numbers NCTM Links: Number & Operations.