(topic: Line Graphs) - Something is amiss with the bliss of Sensible Flats. The reservoir is dry. The town is out of water. And the folks who live there are leaving as fast as they can. But why? When the kids and Digit arrive, they use line graphs to reveal the true story of what happened - and all lines lead to Hacker, the newest resident of Sensible Flats. The Big Idea: You can use a line graph to tell a story about how things change, and make predictions.