This is a dilemma. My colleague asks students to research something and talk about it the next lesson. However, this means the lesson starts with a lengthy discussion and not practical music. I have issues with this, regardless of school policy but SLT need to be kept happy. 10-15 minutes of the lesson is lost on talking about music and not doing it. I get students to take lesson materials home to learn kb or guitar chords, learn lyrics, website revision, structure a performance, set targets for next week. What's your preferred hw?