Long-Term Memory: How Knowledge Sticks and Why It Matters for Teaching
When a pupil walks into your classroom in September, they bring everything they have ever learned. That prior knowledge, stored in long-term memory, is.
When a learner walks into your classroom in September, they bring everything they have ever learned. That prior knowledge, stored in long-term memory, is the raw material your teaching builds on. Understanding how long-term memory works, and how to strengthen it, is one of the most useful things a teacher can know.
For a practical overview of how these ideas apply in lessons, see our guide to working memory in the classroom.
Key Takeaways
- Forgetting is a natural process, but effective teaching can significantly reduce its impact. While Hermann Ebbinghaus (1885) famously demonstrated the rapid decay of memory over time, spaced retrieval practice, where learners actively recall information, strengthens memory traces and makes knowledge more durable (Roediger & Karpicke, 2006). This means regular, low-stakes quizzing is crucial for long-term retention.
- Long-term memory is not a jumble of isolated facts, but an organised network of interconnected schemas. Building on the work of Frederic Bartlett (1932), teaching that explicitly connects new information to learners' existing knowledge structures facilitates deeper encoding and makes retrieval more efficient. Teachers should therefore activate prior knowledge and highlight relationships between concepts.
- The depth at which information is processed significantly determines its long-term retention. According to Craik and Lockhart's (1972) Levels of Processing framework, engaging learners in meaningful elaboration, such as explaining concepts in their own words or making connections, creates stronger and more durable memory traces than superficial rehearsal. Teachers should design activities that encourage deep cognitive engagement.
- Developing automaticity in foundational knowledge is crucial for complex learning and problem-solving. When basic facts and procedures become automatic, they consume less working memory capacity, thereby freeing up cognitive resources for higher-order thinking, as explained by Cognitive Load Theory (Sweller, 1988). Teachers should provide ample practice opportunities for core skills to reach this effortless stage.
What Is Long-Term Memory?
Long-term memory is the brain's permanent storage system. Working memory can only hold a few items for a short time. Long-term memory has no known limits on how much it can store or for how long. A Year 10 learner who learnt the water cycle in Year 5 can still recall it years later. This works if it was learnt well and reviewed regularly.
Squire (1992) split long-term memory into two types. Declarative memory is conscious knowledge of facts and events. Non-declarative memory includes skills and habits. Tulving (1972) stated declarative memory includes semantic memory. It also includes episodic memory (personal events). Semantic memory is key for classroom learning.
For teachers, the practical significance is this: what learners know now shapes what they can learn next. A learner with a rich store of prior knowledge in science can connect new material to existing concepts, encode it faster, and retain it longer. A learner with thin prior knowledge faces a much steeper climb. Building long-term memory is not a luxury; it is the central task of teaching.
Types of Long-Term Memory: A Classroom Overview
| Memory Type | Subtype | What It Stores | Classroom Example |
|---|---|---|---|
| Declarative (Explicit) | Semantic | Facts, concepts, and general knowledge | A learner knows that photosynthesis converts light into glucose |
| Declarative (Explicit) | Episodic | Personal memories and experiences | A learner remembers doing a leaf chromatography experiment in Year 7 |
| Non-Declarative (Implicit) | Procedural | Motor skills and practised routines | A learner writes cursive script without consciously thinking about letter formation |
| Non-Declarative (Implicit) | Priming | Prior exposure that influences later responses | Seeing the word "river" earlier makes a learner faster to identify "delta" on a test |
| Non-Declarative (Implicit) | Conditioned Responses | Learned associations formed through repetition | A learner automatically pauses at a capital letter when reading aloud |
How Memories Move from Short-Term to Long-Term Storage
Bjork (1994) showed spacing repetition helps learners encode information. Baddeley (2000) said the episodic buffer connects new and old memories. This short-term area supports information storage, as Anderson (1983) found.
Synaptic consolidation occurs rapidly after learning (Dudai, 2004). Systems consolidation slowly moves memories to the cortex (Squire & Wixted, 2011). Learners require repeated topic revisits. This ensures lasting knowledge retention (Murre & Dros, 2015).
Teachers should use effective techniques for long-term learning. Spaced repetition, effortful retrieval, and knowledge connections work well (Ebbinghaus, 1885; Karpicke, 2008). "Do Now" activities, where learners recall previous lessons, aid active learning. This method consolidates understanding effectively.
Elaborative encoding boosts memory. Learners build stronger memories when they explain ideas (Craik & Lockhart, 1972). Linking new information to prior knowledge also helps (Bartlett, 1932). Asking learners to explain natural selection, like cheetah speed, aids recall (Anderson, 1983). This method forms lasting memories.
Schema Theory and Knowledge Organisation
Cognitive psychologists use the term 'schema' to describe the mental frameworks through which we organise knowledge. Bartlett's important 1932 studies showed that people don't store memories like photographs. Instead, they rebuild them using existing schemas and fill gaps with what they expect. A learner with rich knowledge about World War II will absorb a new lesson about the Blitz more easily than someone with no background knowledge.
Schemas link related knowledge. New facts connect to schemas and join that network (Anderson, 1977). Isolated facts are easily forgotten. Vocabulary instruction matters; it builds concept scaffolding (Bransford et al, 2000). This helps learners connect and retain new knowledge (Bartlett, 1932).
The relevance for cognitive load theory is direct. Expert teachers do not experience a lesson as a collection of separate facts. Their well-developed schemas allow them to process large chunks of information as single units, freeing up mental bandwidth for the unfamiliar. For learners still building those schemas, each element requires separate processing and places a greater demand on working memory. Good teaching builds schemas step by step, connecting new ideas to what learners already know. This works with how memory is structured, not against it. Reading more about schemas in education gives a fuller picture of how this works in practice.
Encoding Strategies That Build Durable Memory
Weinstein, Sumeracki, and Caviglioli (2018) showed some study methods help learners more. Re-reading and highlighting don't encode memories well. Active recall makes stronger memories that last (Brown, Roediger, and McDaniel, 2014).
Retrieval practice is the most well-evidenced strategy for long-term retention. Roediger and Butler (2011) showed that testing produces greater long-term retention than restudying the same material, even when the tests are low-stakes. In practical terms, this means asking learners to write down everything they remember about a topic before you revisit it. You can use quizzes at the start of lessons, or have learners answer questions without looking at their notes. The act of retrieval strengthens the memory trace. Full guidance on implementing this is available in the guide to retrieval practice for teachers.
Spaced practice spreads learning over time, not just one session. Learners remember topics better when taught in stages (Cepeda et al., 2008). Reviewing material aids retention more than intensive cramming (Rohrer, 2009). Teachers can easily integrate the spacing effect (Ebbinghaus, 1885) using quick recall tasks.
Elaborative interrogation asks learners to explain why facts are true. For example, learners explain headland and bay formation due to coastal erosion. Explaining why hard rock resists erosion builds better memory. This understanding helps learners remember by making connections (Craik & Lockhart, 1972; Anderson, 1983).
Dual coding links words and images for better learning. Paivio's research shows this improves memory. A French Revolution timeline uses dates and pictures. Water cycle diagrams pair labels and visuals. Use dual coding resources (Paivio, n.d.) in the classroom.
Why Learners Forget (and What You Can Do About It)
Ebbinghaus (1885) mapped what he called the 'forgetting curve': a steep decline in retention that begins within hours of learning and flattens out over time. His data, collected through self-experimentation with nonsense syllables, showed that roughly half of new material is forgotten within a day without review. By the end of a week, much of what remains has degraded further.
Anderson (2000) showed interference makes learners forget similar information. Ebbinghaus (1885) found unused memories decay over time. Tulving (1974) explained learners sometimes cannot retrieve stored knowledge. Godden and Baddeley (1975) showed mismatched revision and exam cues hinder learners.
Use these research methods to help learners. Rohrer (2012) suggests interleaving topics, rather than blocking them. Cepeda et al. (2008) show spaced retrieval improves memory. Carvalho & Goldstone (2014) found varied practice builds flexible memory.
Metacognition helps learners succeed. When learners know why they forget, they see gaps in knowledge (Dunlosky & Metcalfe, 2009). Learners then pick stronger study skills. Show Ebbinghaus' (1885) forgetting curve for learner awareness. Explain retrieval beats rereading, though rereading feels good (Karpicke & Roediger, 2008).
Automaticity: When Knowledge Becomes Effortless
Logan (1988) found automaticity means learners use skills without much thought. Fluent readers recognise words quickly, aiding understanding. LaBerge and Samuels (1974) & Schneider and Shiffrin (1977) noted times tables knowledge lets learners problem-solve better.
Sweller (1988) found working memory overload stops learning. Learners need basic facts automatic for algebra. Arithmetic uses needed capacity when not automatic. Higher-order thought relies on memorised knowledge.
Spaced practice builds automaticity, so drill times tables and vocab. This helps learners, according to research (Anderson, 1983). It frees up brain power for complex thought. Teachers build cognitive pathways, as suggested by Sweller (1988).
Automaticity lowers cognitive load during transfer. Learners recall concepts automatically in new situations (Rosenshine, 2012). This lets them focus on unfamiliar aspects. Rosenshine's principles highlight guided practice until fluency. Secure existing knowledge before teaching new material; otherwise, it undermines learning (Rosenshine, 2012).
Connecting New Learning to Existing Schemas
The most efficient way to build durable memory is to attach new knowledge to what learners already know. Ausubel (1968) made this principle that still holds today: "If I had to reduce all of educational psychology to just one principle, I would say this: the most important single factor affecting learning is what the learner already knows." Prior knowledge is not just background. It is the scaffolding on which new learning is built.
Researchers such as Bartlett (1932) showed recalling old knowledge helps learning. Before plate tectonics, ask learners about earthquakes or volcanoes. Before poetry, check knowledge of metaphor and rhythm. Anderson and Pichert (1978) showed these memory tasks link to new content.
The technique of using analogies is particularly powerful for this reason. When a chemistry teacher compares electron shells to theatre seats (front row fills first), they link existing knowledge to new ideas. A learner with no comparison for an abstract concept must store it alone. The learner with the theatre comparison has somewhere to connect it. Scaffolding in teaching works on this principle: give learners the structure that links familiar ideas to unfamiliar ones. Then gradually remove support as the new understanding grows.
Learners with wrong ideas may struggle to learn new things. If learners think heavier objects fall faster, correct them directly. Smith (2023) showed facts alone do not work. Challenge thinking and help learners rebuild their understanding. Direct instruction helps bust misconceptions.
Classroom Strategies for Long-Term Retention
Cognitive science research informs these classroom strategies. They don't need fancy resources and fit existing lessons. Brown et al. (2014) and Weinstein et al. (2018) showed their value. Willingham (2009) and Soderstrom & Bjork (2015) echo this. These researchers make simple, effective teaching easier.
Spaced starters. Begin each lesson with a short retrieval activity covering material from one week ago, one month ago, and one term ago. A five-minute 'Do Now' asks learners to answer three to five questions from memory without notes. This activates prior knowledge, identifies gaps, and strengthens memories of older material. Keep a record of which topics you have revisited. This ensures spacing is truly spread out rather than grouped around topics you find easiest to re-test.
Interleaved practice sets. When setting practice tasks, mix topics rather than grouping all practice on one topic in a single block. A maths teacher might set ten questions covering algebra, fractions, and geometry rather than ten algebra questions followed by ten fractions questions. The short-term effect is that learners find it harder and may feel less confident. The long-term effect is significantly stronger retention and better transfer. Explain this to learners so they understand why the practice feels difficult.
The brain dump. At any point in a lesson, ask learners to close their notes and write down everything they can remember about the topic. This is freeform retrieval: no structure, no prompts, just recall. After two minutes, learners compare their lists with a partner and add anything they missed. Combining individual recall with peer comparison strengthens memory and reveals misconceptions. It also gives you quick feedback about what learners have and haven't remembered. A deeper look at memorisation techniques shows how this fits into a wider toolkit.
Concept maps show how learners link ideas visually. Mapping gaps highlight missing links. Incorrect links show errors (Novak & Cañas, 2006). Mapping strengthens learning (Jonassen et al., 1997). Use this for quick formative assessment. It shows understanding, not just copying (Wandersee, 1990).
Cumulative review works well. Assessments should test knowledge from the whole year, not just recent topics. This helps learners remember everything (Rohrer, 2006). Learners must keep knowledge accessible for later use, like in exams (Brown et al., 2014). It's challenging but useful.
Further Reading: Key Papers on Memory and Learning
Further Reading: Key Papers on Memory and Learning
These five papers form the evidence base for the strategies described in this article. Each is cited by thousands of researchers and has direct implications for classroom practice.
The Episodic Buffer: A New Component of Working Memory? View study ↗
Baddeley, A. (2000). Trends in Cognitive Sciences, 4(11).
Baddeley (2000) added an episodic buffer to working memory. The buffer temporarily stores and integrates information for learners. This connects new information to existing knowledge. Stronger links make encoding more durable (Baddeley, 2000).
Bartlett (1932) studied memory. His "Remembering" research looked at social and experimental psychology. This Cambridge University Press book helps learners understand recall.
Bartlett (1932) found memory reconstructs information, instead of simply reproducing it. Learners altered stories to align with their cultural understanding. Bartlett (1932) showed prior knowledge affects learner recall. Teachers should use existing knowledge in lessons.
Ebbinghaus (1885/1913) researched memory, vital in psychology. His work offers teachers insights into how learners recall facts. Use this research to help learners learn effectively.
Later research by Cepeda et al (2006), Kang (2016), and Agarwal et al (2021) shows that these methods improve learner outcomes. Ebbinghaus showed memory decreases quickly after learning; spaced repetition slows this (1885). Teachers still use his findings on spacing and recall, powerful tools after 100 years.
The Critical Role of Retrieval Practice in Long-Term Retention View study ↗
Roediger, H.L. & Butler, A.C. (2011). Trends in Cognitive Sciences, 15(1).
Roediger and Butler (date not provided) showed retrieval boosts long-term memory. Their review found low-stakes tests beat restudying for learners. They said feedback after retrieval helps learner understanding. Retrieval practice improves academic work. This research helps teachers design revision and assessment.
Cognitive Load During Problem Solving: Effects on Learning View study ↗
Sweller, J. (1988). Cognitive Science, 12(2).
Sweller (1988) found problem-solving can hinder learning. It burdens working memory, reducing long-term recall. Worked examples and practice manage this cognitive load. They improve knowledge transfer to long-term memory, says Sweller.
