You’ve just walked back into what is possibly one of the busiest weeks of the school year. You've just met your new class properly for the first time and you're quietly assessing where they're at. And, if you're anything like every teacher I've ever spoken to, some of what you're seeing right now might make you ask: "Wasn’t that covered already?"
The good news is that it was. And there's a really reassuring, well-evidenced reason why it's not sitting in pupils' minds ready to be retrieved.
The bad news is that most of what any of us learns is forgotten remarkably quickly, and there's over a century of solid evidence to prove it.
Back in 1885, a German psychologist named Hermann Ebbinghaus did something wonderfully odd: he ran an experiment on himself. He memorised lists of made-up, meaningless syllables - nonsense words with nothing to hook them to - and then tested his own memory at intervals afterwards, with nothing to rely on but his own recall. What he discovered became one of the most replicated findings in all of psychology: forgetting isn't a slow fade. It's a steep, fast decline.
His results suggested that we lose around half of newly learned information within about an hour if we don't do anything to reinforce it. We lose most of the rest within a day or two, before levelling off into a much gentler decline. It's worth noting that this isn't some dusty Victorian curiosity - a 2015 study repeated Ebbinghaus's exact method, well over a century later, and found essentially the same curve.
Here's the reassuring bit, though: this has nothing to do with intelligence, effort or how well a previous teacher taught a concept last year. It's simply what happens, by default, to information that goes in once and is not asked for over the summer.
This means that the gaps you may spot this week aren't a characteristic of your new class; they're just memory doing exactly what memory does.
Now consider how much knowledge can be lost over a six week period and you will identify something every teacher instinctively notices the moment they open a new register: summer learning loss.
The research backs up the feeling. Pupil skills, especially in reading, can measurably dip over a long break, and it doesn't hit every child equally. Children from disadvantaged backgrounds tend to lose more, often simply because they have less access outside of school to books, conversations and the everyday experiences that keep vocabulary skills ticking over.
Across a whole primary school career, that quiet, compounding effect turns out to be one of the more significant contributors to the widening attainment gap. Not because anything's going wrong in your classroom, but because of what happens, or doesn't, the moment the classroom door closes for summer.
So, as you're forming your first impressions this week, either through a quiet word, a quick check-in task, or your first look at last year's data in Sonar Tracker, it's worth holding two things in mind at once:
This dip is real, entirely normal, and says nothing about a child's ability
The gap isn't evenly spread, so it's often your most vulnerable pupils who've slipped back the furthest.
That's not a reason to panic. It's exactly the kind of information that should shape your first few weeks of teaching.
Forgetting can be dramatically slowed down, and it doesn't cost a thing. The trick is retrieval. Every single time a child tries to recall something - rather than just being re-taught it from scratch - it strengthens the knowledge. Psychologists call this the testing effect, and it's one of the most robust, well-evidenced findings in the whole of cognitive science.
One well-known meta-analysis comparing spaced versus crammed practice found that spreading retrieval out over time beats cramming by somewhere in the region of 10–30% for retention. That's a big win for very little extra effort and it's brilliant news for the start of term specifically, because it means you don't need to fully re-teach knowledge 'gaps'. Instead, you need to help pupils retrieve what's already in their brains.
If you fancy a genuinely enjoyable read on this whole field, Make It Stick by Brown, Roediger and McDaniel is one of the best entry points available.
This is where the science turns into something you can use on Monday morning. Rather than reteaching all of last year's content from scratch, which is slow and demoralising for pupils, build in short, low-stakes retrieval instead: a five-minute recap quiz on last year's key facts; a "What do you remember?" chat as a way into a new topic; a quick check against last year's Sonar Tracker objectives to see exactly which gaps are real and which are just rusty. Revisiting little and often, spread across September, is much more impactful than one big diagnostic push in week one.
The pay-off for outcomes is real, not just theoretical. Because you're targeting genuine gaps rather than reteaching everything, you reclaim teaching time fast. Because retrieval re-secures knowledge properly rather than papering over it, what you build this term is more likely to stick through to Christmas and beyond. And because this approach helps most with the pupils who had the least reinforcement over summer, it's a quiet, low-cost way of narrowing the very gap that tends to widen every single year.
Better retention, less workload and a fairer start for every child in front of you.
Here's to a September that starts from where your pupils actually are, not where the summer left them looking!