<p>Estimating the impact of different sources of uncertainty along the modelling chain is an important skill graduates are expected to have. Broadly speaking, educators can cover uncertainty in hydrological modelling by differentiating uncertainty in data, model parameters and model structure. This provides students with insight on the impact of uncertainties on modelling results and thus on the usability of the acquired model simulations for decision making. A survey among teachers in the earth and environmental sciences showed that model structural uncertainty is the least represented uncertainty group in teaching. This paper introduces a teaching module that introduces students to the basics of model structure uncertainty through two ready-to-use exercises. The module is short and can easily be integrated into an existing hydrologic curriculum, limiting the time investment needed to teach this aspect of modelling uncertainty. A trial application at the Technische Universität Dresden (Germany) showed that the exercises can be completed in less than two afternoons and that the provided setup effectively transfers the intended insights about model structure uncertainty. The module requires either Matlab or Octave, and uses the open-source Modular Assessment of Rainfall-Runoff Models Toolbox (MARRMoT) and the open-source Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) dataset.</p>