Book excerpt: Controlled investigations, the classic sort of science experiment that involved controlled and dependent variables, have been the source of much scientific knowledge over the years. Learners will engage with science through controlled investigations using Project-Based Learning, or PBL, a student-centered pedagogy that involves active and inquiry-based learning. Each project asks student groups to consider an essential question to form a hypothesis and use technology, research, and experimentation to prove or disprove the hypothesis. Sidebars give learners context for what they're learning in each chapter, and a comprehensive list of useful, PBL-friendly tools is provided for reference.