In lesson planning, it was assumed several decades ago that young students hardly bring any personal ideas or knowledge to science classes, and therefore, good lesson preparation merely needed to decide in which order new terms and content should be introduced using which methods, media, and teaching aids. However, subject-specific surveys show that children and adolescents do form their own ideas about many phenomena from nature and everyday life. To enable or at least facilitate successful learning, chemistry educators and teachers should determine or diagnose what explanations or concepts students have regarding specific topics. Based on this knowledge, teachers are then better equipped to...