The document discusses how Joan Cotter, an engineer and educator with a PhD in math education, developed innovative ways to teach fractions. It describes several fraction models she created, including linear charts, colored bars, and missing parts charts, that make fraction comparisons and concepts easier to understand compared to traditional fraction circles or "fish tank" models. The document advocates teaching fractions using these types of linear representations rather than area models like pie charts that can be more difficult for students to interpret.