For an hour a day at Centennial Arts Academy, a group of fifth-graders get to take a break from the usual structure to learn about anything they want to. The students are part of teacher Dallas Thompson’s genius hour, where kids get to pursue a “passion project” that really interests them — no tests or curriculum, just the joy of learning. William Scott, 10, used genius hour to build a model roller coaster, learning about engineering and math in the process.