Planning for and teaching somebody else's class can be a daunting process, especially for a trainee teacher like the author, who still has to gain all the knowledge and experience of managing a group of 36 10- and 11-year-olds. As part of her degree studies, the author had to plan, with a group of other trainee teachers, a series of lessons on food and nutrition education, based on information they had received about what the children had already been learning. Their previous topic in science was irreversible and reversible changes; they had also been looking at microbes. So, they decided to look at the role of different microbes in food. After the first session the trainee teachers found that the children did not really come away knowing much more than at the start. So, they adapted their planning to take an investigative approach to the second session with them. The second session is presented in this article.