"It is a must-have technology," said Shawn Mishler, director of communications technology at Columbia's privately run elementary school. "My dream school would have 7-foot-diagonal, in-wall units in every classroom. That, however, requires a lot of in-wall space, which is not practical in Manhattan." During a recent visit to the school, students in a third-grade class used the board to demonstrate solutions to math problems. The children drew on the board with their fingertips and explained to the class how they came up with their answers.