A German school lesson, the Schulstunde, lasts 45 minutes, not an hour. Lessons once lasted 60 minutes. On 22 August 1911, the Prussian minister of culture, August von Trott zu Solz, ordered that a lesson at all higher schools be set at 45 minutes. The reason was practical. With shorter lessons, all 30 to 32 weekly lessons could be placed in the morning. According to the German Historical Museum, a pedagogical lexicon of 1917 suspected that the change was made for reasons of rationalization.