In this study we describe the support provided by a biology teacher during learning using a web-based research simulation that makes use of authentic research practices in genetics, including the use of a heuristic strategy to compare mutated and normal versions of a character at all the organisational levels. Authentic scientific practices include the use of conditional knowledge--namely coordination between declarative and strategic knowledge--which is not typically found in regular school tasks. Thus, it is unlikely that students will be able to carry out such coordination without guidance from their teacher. Our research question was: what kind of support does a teacher provide during enactment of the research simulation and how does it facilitate students' ability to coordinate between declarative and strategic knowledge? We observed one teacher and her students during the enactment of the research simulation in class. Our analysis revealed the support given by a teacher to promote students' use of conditional knowledge in a high-school biology classroom, was similar to the use of such knowledge by scientists in the course of performing authentic research.