Forty-nine minutes a week: what a proper trial of AI lesson planning actually found
What happened
On 6 October 2026, results were published from a trial testing whether an artificial intelligence tool could reduce the time primary teachers spend planning lessons. The tool is called Aila. It is a free AI lesson assistant built by Oak National Academy, the government-backed body that provides curriculum resources to schools in England. The trial was commissioned by the Education Endowment Foundation, known as the EEF, and carried out by the National Foundation for Educational Research. It was a randomised controlled trial, which is the strongest design for this kind of question: teachers were allocated at random either to use the tool or not, so that any difference between the groups is more likely to be caused by the tool itself. It involved 464 primary teachers across 108 schools in England, teaching Year 3 to Year 6, over ten weeks in autumn 2025. The result on time was clear. Teachers using Aila spent an average of two and a half hours a week planning lessons and preparing resources. Teachers not using it spent three hours and 19 minutes. That is a saving of about 49 minutes a week, or around 24%. On quality, independent assessors looked at the lesson resources produced by both groups. The materials from the Aila group were judged no worse in quality than those from teachers who had not used the tool. The EEF gave the evaluation a high security rating, meaning it considers the design rigorous, the delivery strong and the time-saving finding reliable. But the report was not a straightforward endorsement. The tool was used sparingly. Use fell away over the ten weeks. Teachers' opinions of it were mixed. And newer teachers were more likely to use it to create lesson plans than more experienced colleagues.
Why this matters
Teacher workload is one of the main reasons people leave teaching, and planning is one of the biggest parts of it. Forty-nine minutes a week is close to an hour, every week, for a whole year. What makes this trial unusual is that it exists at all. The education technology market is full of products that claim to save teachers time. Very few of them have been through a randomised controlled trial run by an independent evaluator. Most evidence offered to schools is a case study supplied by the company selling the thing. So the significance is partly the finding and partly the standard. A free tool, tested properly, with results published whether or not they flattered it. The quality finding matters just as much as the time one. The obvious worry about AI-written lesson plans is that they would be generic, shallow, or subtly wrong, and that the time saved would be paid for in worse teaching. Independent assessment found the resources were no worse. That is not the same as better, and it is worth being precise about that. The pattern among newer teachers is the most interesting detail. A teacher in their second year has far less of a back catalogue to draw on than one with fifteen years of resources saved up. It makes sense that the tool helps them most. It also raises a question nobody has answered yet: whether leaning on an AI assistant early in a career helps a teacher build expertise, or slows that process down.
What the evidence actually says
This is a good trial and it still has limits worth understanding. It measured time spent planning and the quality of the resources produced. It did not measure what children learned. No claim is being made that pupils did better, because that was not tested. It ran for ten weeks with Year 3 to Year 6 teachers in England. It does not tell you about secondary teachers, early years, special schools, or what happens over a full academic year. The drop-off in use is a genuine finding, not a footnote. A tool that saves time but that teachers gradually stop using is telling you something about how it fits into real working life. The 24% saving was measured among those allocated to use it, and they used it sparingly, which makes the saving more striking in one sense and more fragile in another. Mixed teacher opinion matters too. A tool people find useful but do not much like will struggle to stick. And the broader caution about AI in classrooms still applies. AI tools can produce confident text that is factually wrong. Nothing in this trial removes the need for a teacher to read and check what the tool produces. The trial's quality finding depends on teachers doing exactly that.
Practical advice
For teachers and school leaders: Aila is free and provided by Oak National Academy, so trying it does not require a budget decision or a procurement process. That is a genuine difference from most edtech. If you do try it, treat it as a first draft generator rather than a finished product. The evidence of no quality loss comes from teachers who reviewed and adapted what it made. If you are a newer teacher, this trial suggests you are likely to get more out of it than colleagues with years of resources banked. That is not a criticism of you; it is a sensible use of a tool. If your school is being sold an AI product, ask for an independent evaluation. Ask specifically whether a randomised controlled trial has been done and who ran it. If the answer is a case study from the supplier, that is worth knowing before you spend money. For parents: AI involvement in lesson planning is not the same as AI teaching your child. If you want to know how your child's school uses these tools, ask at parents' evening. Schools are generally happy to explain, and more schools now have a written policy than did a year ago. And for anyone worried about teacher workload in their child's school: the useful question to a head teacher is not "are teachers busy" but "what have you taken off their plate this year".
What to know
A randomised controlled trial of 464 primary teachers in 108 English schools found that Oak National Academy's free AI lesson assistant, Aila, cut lesson planning time by about 24%, or 49 minutes a week. Teachers using it spent two and a half hours a week planning, against three hours 19 minutes for those who did not. Independent assessors judged the resources produced to be no worse in quality. The EEF rated the evaluation highly secure, and the results were published on 6 October 2026. The caveats are real. Teachers used the tool sparingly and use declined over ten weeks. Opinions were mixed. Newer teachers used it more than experienced ones. And the trial did not measure what pupils learned. The wider point is the standard this sets: a free classroom AI tool put through a proper independent trial, with the uncomfortable findings published alongside the good ones. Sources: Education Endowment Foundation, 'Lesson planning using AI lesson assistant, Aila - Teacher Choices Trial', October 2026, https://educationendowmentfoundation.org.uk/projects-and-evaluation/projects/aila-teacher-choices-trial ; Tes, 'Do teachers find Oak AI lesson planning tool helpful?', 6 October 2026, https://www.tes.com/magazine/news/general/do-teachers-find-oak-ai-lesson-planning-tool-helpful-aila ; EdTech Innovation Hub, 'Oak's Aila saves primary teachers 49 minutes a week on lesson planning, EEF trial finds', 6 October 2026, https://www.edtechinnovationhub.com/news/oaks-aila-saves-primary-teachers-49-minutes-a-week-on-lesson-planning-eef-trial-finds This article is for general information. It is not health advice, and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.
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