In 1958, the educationalist Wolfgang Klafki published an essay with the title Didaktische Analyse als Kern der Unterrichtsvorbereitung, didactic analysis as the core of preparing a lesson. From the late 1950s, it became the leading guide in the training of new teachers. Its questions include Was bedeutet es für die Schüler heute? (What does it mean for the students today?) and Was wird der Inhalt für die Schüler morgen bedeuten? (What will the content mean for the students tomorrow?) In teacher training, a trainee teacher writes a lesson plan for an assessed lesson. It analyzes the class, the subject and the method before it sets out the sequence of the lesson, phase by phase, with a time for each. The sequence plan is called das Drehbuch der Unterrichtsstunde, the screenplay of the lesson. Some training programs prescribe a length, for example eight to ten pages.