Newly available data is revolutionizing the way teachers and students collaborate. Right now, most teachers spend hours grading homework and tests and then copying everything down into spreadsheets they made themselves. And after all that, teachers often only have a partial sense of how each student is doing—based on rows and rows of numbers and whatever qualitative insights they can keep in their head. But online systems can give teachers pinpoint diagnostics for each student at the touch of a button. At Summit Public Schools—a charter school network that started in California—students and teachers collaborate on the Personalized Learning Platform, which generates troves of data. Teachers not only get to see how each student did on the days’ assignments; they can use predictive analytical tools and sophisticated visualizations to determine whether students are on track, so they are continually adjusting in real time to target the areas where students are having trouble.