A group of middle school girls is puzzling over a pie chart about reading habits in the U.S. Their “math designer” stands at the front of the room, encouraging students to share what they “notice and wonder.” A data talk, as it’s known, is meant to empower students to ask questions about the data-filled world around them and embrace uncertainty. Teachers aren’t experts but fellow explorers. Welcome to Youcubed, a Stanford-designed data-science course. This one was taught at an all-girls STEM middle school in Palo Alto, California, where tuition costs more than $50,000. Across the nation, schools are incorporating Youcubed and similar coursework into their math curricula to engage struggling students. In some states, such classes have become a substitute for Algebra 2. Educators and administrators in recent years have been eager to reimagine math instruction. Troubled by high failure rates in traditional high school classes, many have embraced trendy curricula that seek to make math more fun, incorporating coursework that feels more relevant to students than, say, dividing p