A group of middle school students gather around a dining room table after a day of school work discussing the question, “How many integers between 500 and 1000 contain both the digits 3 and 4?” While some are busily writing out notes on scratch paper and consulting their TI-84 graphing calculators, one student picks up a marker on to a white board propped in the corner. “Here, let me show you …..,” he says. more