In this article, the author describes a chemistry gas experiment that she developed with the intent of integrating inquiry and Problem-Based Learning (PBL). The lab activity follows the principles of Ambitious Science Teaching (AST). Teachers (1) engage students with important science ideas, (2) elicit students' ideas while making visible what students currently know about the science being taught, (3) guide sense-making talk around investigations and lab activities to support changes in thinking, and (4) develop evidence-based explanations by scaffolding students' efforts to put everything together. Additionally, the lesson plans incorporate a "Driving Question", a themed question written on the board (SMART, white or blackboard) that supports inquiry and PBL by organising and focusing students' questions and linking them to the learning objectives of the activity.