Oak National Academy. Teachers in England spend hours a week preparing lessons. Oak's Aila assistant drafts lesson plans and resources from the national curriculum. In a trial of 464 teachers in 108 schools, commissioned by the Education Endowment Foundation and run by NFER, Aila users spent about 2.5 hours a week preparing versus 3 hours 19 minutes, and independent assessors judged their resources no worse. Teachers edited the output, used it for about 7% of lessons, and used it less over time.