An observational project for a large class – determination of the duration of the sidereal day

Having students confront the real night sky is difficult for a large class. The determination of the duration of the siderealday is however a project that students can do on their own without specialized equipment. The project provides anintroduction to how observational science is done because students must devise the observational procedure, maketimings, analyse them, and present results including uncertainties in a report. The experience of running this project aspart of a first-year university introduction to the grand ideas of physics is described, with suggestions for improvements.Almost a third of students reported results within 1 second of the accepted value