‘Air Pump 2’ is a design-build-test (DBT) exercise at the start of the first-year project module in Mechanical Engineering (ME) at École Polytechnique (EPM). ME students have gained prior experience at ‘Air Pump 1’ 16 weeks before, a playful challenge on Orientation week. In ‘Air pump 2’, teams of 4-6 students work from a ‘functional requirement’ sheet. The context is that of corporations competing for a ‘contract’ for 10,000 pumps. The flow-pressure-volume pre-tests of a prototype, materialised by apparatuses not fully appropriate, set the context for a ‘Test’ phase in two rounds, on ‘new’ and ‘aged’ pumps. Students keep track of test scores and costs (an opportunity to discuss breach of ethical behaviour). A 20 min class reflection follows a first 10 min individual reflection without prompts. On the upside, many students do not take the embedded 10 min break, and work on their pump. On the downside, only a minority pursue the reflection off-hours, and too small a percentage of the pumps bide by the constraints or actually work. Informal surveys point to this as a probable cause of disengagement from subsequent autonomous reflection.