The document discusses the optimal length and frequency of language lessons for children. It notes that lessons over an hour are too long and exhausting for children, while lessons under 30 minutes are too short and fragmented. The best approaches are either to combine shorter lessons into longer blocks of time or spread lessons out over the week. Combining lessons helps children retain information better between sessions but requires more preparation. Longer individual lessons are more efficient but risk behavior issues, while shorter sessions are more demanding on teachers and students.