Most of what students call revision is rereading. It takes a long time, it feels like work, and it does less for what they'll remember in June than a few minutes of trying to recall the same material without looking.
What the evidence actually says
Three sources are worth knowing about, and it's worth being clear about what each one covers.
Roediger and Karpicke (2006), "Test-Enhanced Learning: Taking Memory Tests Improves Long-Term Retention", Psychological Science 17(3). Students who were tested on material remembered more of it a week later than students who spent the same time restudying it. This is the finding the whole idea rests on. (https://doi.org/10.1111/j.1467-9280.2006.01693.x)
Karpicke and Blunt (2011), "Retrieval Practice Produces More Learning than Elaborative Studying with Concept Mapping", Science 331(6018). Here retrieval did better than a well regarded active study technique, not just better than passive rereading, which makes it a fairer comparison. (https://doi.org/10.1126/science.1199327)
Dunlosky and colleagues (2013), "Improving Students' Learning With Effective Learning Techniques", Psychological Science in the Public Interest 14(1). A review of ten study techniques. It rated practice testing and spreading practice out as high utility, and rated rereading and highlighting as low. Rereading and highlighting are what most students do. (https://doi.org/10.1177/1529100612453266)
What they do not say
They don't say retrieval practice raises GCSE grades. The strongest studies measure how much people remember in controlled conditions, often with undergraduates, over weeks rather than over a two year course. The classroom evidence is thinner, and anyone quoting a grade improvement from this literature is going further than it goes.
Our position on citing evidence, including how we label our own numbers, is on the evidence page.
What that means on a Tuesday
The classroom version is fairly ordinary:
Short. Six to ten questions on one narrow thing. If it takes a whole lesson, it's a lesson rather than a retrieval task.
Closed book. If students can see the answer, they're reading. The notes come out afterwards.
Low stakes. Nothing recorded. The memory effect doesn't need the mark to count, and once it does count, students behave differently about getting things wrong.
Corrected. The recall does the work, but the correction is what stops a wrong answer settling in. Feedback that arrives next lesson has usually come too late.
Spaced. Coming back to a topic after a gap is harder, and better, than going over it again the same week.
Where the product fits
The last two are where software genuinely helps. Answers are checked as the student works, so the correction arrives in the same minute as the mistake. Each question also records how many attempts it took to get right, which tells you whether a student nearly knew it or guessed.
None of it needs marking, and that's the practical reason spacing survives a real term. A routine you have to mark is usually the first thing to go.
For the practical half, what twelve minutes looks like and the seven ways it stops working, see running retrieval practice in a lesson.
Start with the question-dense activities below, or browse everything by specification on the revision pages. The official past papers are there for when you want real exam questions rather than practice ones.