The authors have developed a first-year fluids course for a class of around 230 aerospace, civil and mechanical engineering students. This paper aims to show how the teaching and assessment methodology was applied to the challenge of a large class. The lectures featured formal teaching interspersed with active learning elements. Smaller group (about 25-30 students) tutorial classes involved student practice. A 10-minute test occurred in each tutorial during weeks 3-11. Each test was based on the previous week's lecture material and the marks contributed towards 20% of the course mark. A condition for passing the course was that a student must pass at least six of the nine tests. The assessment promoted student involvement with the course--tutorial attendance was greater and more uniform than previously and exam performance improved significantly. Students recognised that the assessment system was useful in encouraging continuous learning over the semester and building confidence. (Contains 11 figures.)