👋 Hey {{first name | DistillED reader!}}
In this second edition of the CLT series, we're exploring element interactivity.
You'll know the problem even if the term is new: a class learns every key term for a unit and can define each one perfectly. But, when you ask them to use the terms together, to analyse a quotation or rearrange a formula, everything falls apart.
⚗️ The Cognitive Load Theory Series: This edition is part of a new multi-part DistillED series translating contemporary CLT into classroom practice.
Element Interactivity ← you are here
The Split-Attention Effect
In this edition
📊 Do Now: Quick Poll!
When students struggle with complex content, what do you usually do first?
What Is Element Interactivity?
Element interactivity describes how much the pieces of information in a task depend on one another. When they interact, students must process them simultaneously in working memory to make sense of the task. Sweller and his colleagues define an element as anything that needs to be learned or processed, such as a word, symbol, fact or step (Sweller, Ayres & Kalyuga, 2011).
Some content can be learned one piece at a time. For example, a student can learn that Cu is the symbol for copper without knowing that Fe is the symbol for iron. Each element stands alone, so element interactivity is low.
Other content only makes sense as a whole. To solve (a + b)/c = d for a, a novice has to hold every symbol, and the relationships between them, in mind at once. Change one part and the others are affected. Element interactivity is therefore high. In reality, element interactivity exists on a continuum from very low to very high; “low” and “high” are simply useful shorthand (Stokke, 2026).
Two things make this idea more useful than it first sounds.
First, element interactivity is different from difficulty. Learning a thousand French nouns is hard work, but it is hard because there are so many of them. Each noun can still be learned on its own, so each one places relatively little strain on working memory.
Second, it depends on what students already know. Zach Groshell gives a good example: “Sam sat on the mat” is high in element interactivity for a brand-new reader, who must decode, blend and hold every word in mind. For a fluent reader, however, the whole sentence can be processed almost as a single unit (Groshell, 2025).
In typical DistillED fashion, here's what element interactivity is, and what it isn't:
👎 Element Interactivity IS NOT:
The Same as Difficulty → A long vocabulary list is hard work, but each word can be learned on its own.
The Same for Every Student → What overloads a novice can be easy for an expert (Chen, Paas & Sweller, 2023).
A Reason to Avoid Complex Content → The relationships are usually what we most want students to learn, so we plan for them.
Something You Need to Count → A quick judgement is enough: can this be learned piece by piece, or only as a whole?
👍 Element Interactivity IS:
About Connections → The load comes from how many parts depend on each other.
Relative to Prior Knowledge → Secure knowledge turns many parts into one familiar pattern.
A Planning Lens → It shows you where a lesson will be hardest before you teach it.
The Reason Sequence Matters → It helps you decide whether to explain first or let students try first.
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Why Does Element Interactivity Matter?
Element interactivity explains why the same lesson can land with one class and fall flat with the next. It also offers a clearer way to think about one of teaching’s oldest debates: should we explain first, or let students try first?
Greg Ashman, Slava Kalyuga and John Sweller tested this with Year 5 students learning about light and energy efficiency. When the content was made more complex, students who received explicit instruction before problem-solving outperformed those who tried the problems first, on both similar and transfer problems (Ashman, Kalyuga & Sweller, 2020).
A later study with 85 middle school science students added the nuance. Explicit instruction first worked better for students with less knowledge, for whom the content was high in element interactivity. Investigation first worked better for students who already knew more, for whom it was lower (Zhang & Sweller, 2024).
So the answer depends on the meeting point between the content and the class. Sweller makes the same point himself: in a recent podcast, he said the message he most wants teachers to take away is that content where many parts depend on each other needs to be taught very differently from content that can be learned one piece at a time (Thought Stretchers, 2026).
This is also why difficulty can mislead us. We tend to slow down for topics that feel big and rush the ones that look small. But a short task with tightly connected parts can ask far more of working memory than a long list of separate facts.
“A low intrinsic cognitive load needs to be distinguished from levels of task difficulty.”
The distinction changes which strategies work. Retrieval practice, for example, gives its most reliable gains on immediate tests with simpler material. In one set of experiments, the testing effect was larger and more likely with lower element interactivity content (Hanham, Leahy & Sweller, 2017). High-interactivity content usually needs explaining and modelling before it's ready to be retrieved.
The diagram below puts these findings together. The question to ask is how many parts of the content depend on each other, and how secure your students' knowledge of those parts already is.
The same content can sit in different boxes for different classes. As students' knowledge grows, a lesson moves right, and the teaching can shift from explaining first to handing over.
You can't see inside your students’ heads, and you don't need to. Researchers can count the elements in a task, but what students already know can only be estimated, through teacher judgement or quick knowledge checks (Chen, Paas & Sweller, 2023). That’s something teachers already do every day.
👉 Read more on why showing comes before asking here: Explicit Instruction
🎥 Watch this 3-minute video explainer on knowledge – why what students already know changes how much they can think about at once.
🎯 Teaching for Attention Playbook
My new Teaching for Attention Playbook is a 70+ page, evidence-informed guide that breaks down the science of attention and provides 6 practical strategies to support teachers.
How Do I Plan for Element Interactivity?
To use this idea, look at a lesson the way a novice will meet it: as a set of parts, some of which must be held together. The five steps below take you from spotting those moments in your plan to handing the thinking over to students.
Step | Explanation | Example |
|---|---|---|
1. Separate the Parts From the Connections
| List what students need for the task. Mark the items that stand alone, like terms, symbols and facts. Then mark the moments where several of them must be combined. Those moments are where the load builds. | Year 10 English: "Simile, imagery and connotation are each one term. Explaining how two images build Lady Macbeth's guilt means combining all of them with the context. That's where I'll slow down." |
2. Check What’s Already Secure
| Before teaching, check the parts the task depends on. A quick test: show a formula, diagram or step for a few seconds, take it away, and ask students to reproduce it. Those who can are already treating it as one familiar chunk. | Year 9 Maths: "I'll show this formula for five seconds. Now boards down, and write it from memory." |
3. Pre-Teach the Parts on Their Own
| Teach and retrieve the terms, symbols or steps separately first. When students meet the full task, each part is already secure and working memory is free for the connections. Researchers call this pre-training (Sweller, Ayres & Kalyuga, 2011). | Year 8 Science: "Before we calculate density, tell me what mass means, what volume means and the unit for each. Whiteboards up." |
4. Model the Whole Before They Try It
| Show a complete worked example and narrate how the parts connect. Then give a similar task with your example still visible (Ashman, Kalyuga & Sweller, 2020). | Year 11 History: "Watch how I link the economic cause to the political one. Then you'll do the same with the social cause, with my paragraph still on the board." |
5. Hand Over as Knowledge Grows
| When most of the class shows the parts are secure, let students attempt problems or investigations before you explain (Zhang & Sweller, 2024). If they're still using those problems to work out what to do, they aren't ready yet, so go back to worked examples (Stokke, 2026). | Year 9 Science: "You know how to calculate density. Before I show you anything, predict which of these objects will float, and explain why." |
Take a short sequence on density in Physics. Students need two terms, mass and volume, and the relationship between them. The terms can be learned on their own, so teach them first and quiz them until they’re secure. The relationship is where the parts depend on each other, so model one full calculation before students try one. A week later, once the calculation is secure, the same class can investigate why some objects float. Density is now one familiar idea, not three moving parts.
Notice what changed across that sequence. The content stayed the same. What students knew grew, and so the teaching shifted with it.
Until next week!
— Jamie
If you want more:
👉 Read Cognitive Load Theory: the first edition in this series, and the big picture this edition builds on
👉 Read Small Steps: Rosenshine's routine for presenting complex content in manageable chunks
👉 Read Worked Examples: how to model the whole before students try it
📥 Free One-Page Guide
Cognitive Load Theory Unpacked One-Page Guide
To help you put this into practice, download Cognitive Load Theory Unpacked: a one-page guide to six strategies for managing what students must hold in mind, from checking prior knowledge to fading guidance as knowledge grows. Useful for your own planning, in coaching conversations, or during team PD.
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