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In the first ⚗️DistillED edition of 2026, we focus on retrieval practice — one of the most reliable findings in the science of learning.
We’ll clarify what retrieval practice actually is, why it sometimes falls flat, and how to implement it in ways that genuinely strengthen learning.
In this edition
📊 Quick Poll!
Which “lethal mutation” of retrieval practice do you see most often?
What is Retrieval Practice?
Retrieval practice means deliberately asking students to bring information to mind from long-term memory, rather than re-reading, copying, or listening to it again. Classic examples of retrieval practice include:
Answering questions without notes (cold questions, low-stakes quizzes)
Recalling definitions or processes (self explanation, flashcards)
Writing what you remember before checking (brain dumps, whiteboard responses)
When students are asked to retrieve information after some forgetting, the effort required to reconstruct knowledge strengthens memory and makes learning more durable over time. As Robert Bjork describes, this benefit depends on desirable difficulty: retrieval needs to be effortful enough to stretch memory, but not so hard that weak understanding or excessive complexity overwhelms learning.
Effective retrieval sits in the space of ‘healthy struggle’—where students are challenged to think hard, effortfully reconstruct knowledge, and strengthen memory without tipping into cognitive overload. In a nutshell, here is what retrieval practice is and is not:
👎 Retrieval practice is not:
Asking students to struggle before understanding is secure (“Write everything you remember about mitosis — we’ll figure it out as we go.”).
Encouraging guessing when knowledge is fragile (“Just have a go — it doesn’t matter if you don’t really know the ins-and-outs yet.”).
Demanding complex explanations too early (“Explain why the Treaty of Versailles caused World War II, using evidence, without looking at your notes.”).
👍 Retrieval practice is:
Strengthening existing memory traces (“Yesterday we learned the stages of mitosis. Without your notes, list the stages in order — we’ll check after”).
Making learning more durable over time (“Last week we learned this. Let’s bring it back now and see what still sticks before we move on.”).
Consolidating teacher instruction (“I’ve just modelled the process and we practised it together. Now, complete just step one on your whiteboard.”).
Being precise about what is worth remembering “Don’t try to recall everything. Focus on the three features we said really matter.”).
Why does Retrieval Practice Matter?
The testing effect (retrieval practice) is one of the most replicated findings in cognitive science. Studies consistently show that retrieving information leads to better long-term retention than re-reading, highlighting or passive review.
Researcher Jeffrey Karpicke captured this idea succinctly when he wrote that “learning is altered by the act of retrieval itself” (Karpicke, 2012) What’s more, Paul Kirschner and colleagues make a closely related point in their paper ‘Why Minimal Guidance During Instruction Does Not Work’ noting that:
“The aim of all instruction is to alter long-term memory. If nothing has changed in long-term memory, nothing has been learned.”
In other words, retrieval changes memory—and when long-term memory changes, learning has taken place. Each successful act of retrieval strengthens existing schema (networks of knowledge) and increases the likelihood that the information can be recalled again in the future.
In neuroscientist Jared Cooney Horvath’s new book The Digital Delusion, he cleverly describes memory and retention like skiing through fresh snow:
“Ski the same route hundreds of times, though, and you’ll cut a lasting trail into the hillside — one that can withstand even the fiercest storm.”
Like skiing through fresh snow, new learning leaves only a faint trail at first. Without reinforcement, that trail quickly fills in and disappears. Retrieval practice doesn’t create the path—it forces learners to travel it again, compacting the snow and making the route clearer and easier to follow next time. Only once a path exists can retrieval make learning durable. This progressive strengthening of schema is visualised in the graphic below:
However — and this is crucial — retrieval does not work equally well in all conditions.
When retrieval is not designed carefully, it can lead to shallow learning or unnecessary cognitive overload. This aligns closely with Carl Hendrick’s argument about lethal mutations of retrieval practice. When retrieval is applied incorrectly, it can stop being a desirable difficulty and start being an undesirable one. For example:
Lethal Mutation 1: Retrieval practice is introduced too early
Lethal Mutation 2: Retrieval practice is applied to complex material
Lethal Mutation 3: Retrieval practice is poorly aligned with curriculum priorities
Lethal Mutation 4: Retrieval practice is stacked with too many steps at once
The challenge isn’t whether to use retrieval—it’s how to design it with high fidelity to the evidence so it actually strengthens learning. Let’s unpack this…
How do I Implement Retrieval Practice?
Carl Hendrick’s Seven Essential Principles provide a useful guide to great implementation of retrieval practice. They help translate research into practical design rules you can apply when planning curriculum and lesson retrieval tasks:
Principle 1: Retrieval is most powerful when it follows partial forgetting.
Principle 2: Retrieval should strengthen memory, not measure performance.
Principle 3: Retrieval needs to be effortful but not cause cognitive overload.
Principle 4: Retrieval needs to be repeated over time to make learning durable.
Principle 5: Retrieval must be tightly aligned to curriculum priorities.
Principle 6: Retrieval needs to be taught explicitly.
Principle 7: Retrieval must be frequent and low-stakes.
To support this, here is a practical six-step process for designing more effective retrieval practice with clear classroom examples:
Step | Explanation | Example |
|---|---|---|
1. Teach Before You Retrieve
| Retrieval strengthens existing memory traces; it cannot create understanding. Students must receive clear explanation, modelling, and initial guidance before retrieval begins. | “Watch how this works first. We’ll come back and retrieve it shortly.” |
2. Build in Processing Before Recall
| Students need time to read, listen, discuss, or practise with support so knowledge enters long-term memory before notes are removed. | “With your notes open, summarise the three key steps in your own words.” “Rehearse the three key steps by explaining them to your partner.” |
3. Retrieve Curriculum-Critical Knowledge
| Retrieval amplifies whatever is recalled, so questions must target core knowledge and learning goals, not surface details or trivia. | “Retrieve the order of the atomic models — not the years they were proposed.” |
4. Match Retrieval to Knowledge Type
| Retrieval works best for discrete facts, features, steps, and vocabulary. Complex explanations should be built later from retrieved components. | “Which model came after Thomson’s?” rather than “Explain how atomic theory evolved.” |
5. Adjust Effort Level and Fade Support
| Start with cues or partial prompts to ensure successful retrieval, then gradually remove support as knowledge becomes more secure. | First: label a provided diagram. |
6. Space, Revisit, and Respond
| Retrieval must return across lessons and units. Student responses should guide reteaching, clarification, or adjustment rather than judgement. | “Two questions from last week, one from last term — then we’ll address any gaps.” |
Retrieval practice works — but only when it’s designed thoughtfully. It’s not about more stuffing in more quizzes. It’s about helping students retrieve the right knowledge, at the right time, with the right level of support.
Until next week — Jamie
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Free Retrieval Practice One-Page Guide
Retrieval Practice Principles One-Page Guide Written by Carl Hendrick
To help you put these ideas into practice immediately, download the Retrieval Practice Principles guide based on ‘Making Retrieval Practice Actually Work: Seven Essential Principles for Teachers to Know’ an important blog post Carl Hendrick.
⚗️DistillED+ Exclusive Content
This week’s ⚗️DistillED+ members get access to a Retrieval Practice CPD PowerPoint and a Printable Retrieval Checklist, breaking down how to design retrieval that targets the right knowledge, is spaced over time, and strengthens learning without overload.
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