The aim of this study was to design and evaluate an inquiry- and activity-based learning unit for the classroom that uses biological collections to teach key evolutionary concepts and to support the understanding and appreciation of the work of a museum. The unit consisted of three parts that focused on the most important tasks of museums: collecting and conserving, researching and exhibiting. The students created their own collection, performed research surrounding it and then designed an exhibition. Seventy-six secondary sixth- and seventh-grade students participated in the testing of the prototype unit. For evaluation, we carried out a pre-/post-test design using a questionnaire that assessed content knowledge and learning enjoyment. The mean knowledge score of the post-test indicated significant learning gains compared to the pre-test results. The test on learning enjoyment showed best mean values for actions that included the collection, compared to results of the theoretical parts of the unit. This approach demonstrates that the learning unit offers the opportunity to experience the tasks of a museum at first hand and to acquire knowledge about evolutionary science and evolutionary principles.