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Session 3. Cognitive Load in Lesson Design
Objective. By the end of this session, you will be able to apply cognitive load principles to simplify a lesson's information density.
A slide that looks rich to you can be a wall to a student who meets the topic for the first time. Cognitive load theory gives you a practical test: what does this student have to hold in mind at once, and how much of it is really the lesson? In a class of 35 with mixed readiness, small design choices on a slide or a worksheet decide who keeps up and who quietly stops.
Key ideas
Three Kinds of Load
- Intrinsic load — difficulty inherent to the content itself (a genuinely hard concept)
- Extraneous load — difficulty added by how the material is presented, not the content itself
- Germane load — effort spent actually building understanding, the load you want
- Working memory (Session 1) is the shared bottleneck all three compete for
Reducing What You Can Control
- Cut extraneous load first: remove decorative visuals, redundant narration of on-screen text, split-attention layouts
- Manage intrinsic load through sequencing: pre-teach a prerequisite before combining it with something new
- Signal what matters: headings, highlighting, and clear structure reduce the effort of finding the point
- Free capacity through these two moves — then, and only then, ask for germane effort
Redesigning an overloaded slide
Element interactivity: why the same topic feels different
Intrinsic load is not only about how hard a topic is. It depends on how many separate pieces a learner must think about together, which John Sweller and colleagues call element interactivity. Solving 3x + 5 = 20 is easy for a student who already treats "balance both sides" as one idea, but heavy for a student who sees five unrelated steps.
So the same lesson can be light for one class and overloaded for another. Before you teach, ask which pieces your students already have as one unit. Teach the missing pieces separately first, then combine them. This is why a quick check of prerequisites often saves more time than any new slide design.
Worked examples, then fading support
For beginners, studying a fully worked example usually teaches more than being asked to solve a similar problem alone, because searching for a method eats working memory. Sweller's research supports a simple sequence: show a complete worked example, then one with a step missing, then a problem to solve alone.
The advice reverses as students grow more skilled. Detailed steps that help a novice can become unnecessary and even tiring for a student who already knows the method (the expertise reversal effect, associated with Kalyuga). So watch your class and remove support as competence appears; do not keep one fixed style for all students all year.
Examples from the classroom
Grade 7 physics, Samarkand
Scene. Malika's slide on the water cycle has a colourful photo of the Zarafshan river, 120 words of text, a diagram on the right and its legend at the bottom. She reads the text aloud while students try to match legend numbers to arrows. After the lesson only a few can name the stages. Next time she removes the photo, puts labels directly on the arrows and shows the four stages one at a time.
Insight. Split attention and redundant narration are extraneous load; putting labels in the diagram and revealing in steps leaves capacity for understanding.
Grade 6 mathematics, Uzbek-medium class
Scene. Aziz teaches fractions of a cotton field: 3/4 of 120 hectares. Instead of asking students to start at once, he solves one example on the board with each step named. Then he gives 2/5 of 150 with the last step blank, and finally 3/8 of 160 to solve alone. Students who struggle keep the first example open on their desks.
Insight. Worked example, then partly completed, then independent practice is the fading sequence that lowers load for novices.
Grade 9 chemistry, Russian-medium class
Scene. Dilnoza wants to teach balancing equations, but half the class hesitates over formulas such as H2SO4. She spends ten minutes first on a short drill writing formulas from names, using the textbook table. Only then does she introduce balancing with coefficients. The following lesson, students handle the equation 2H2 + O2 -> 2H2O with far fewer stops.
Insight. Intrinsic load is managed by sequencing: make a prerequisite automatic before combining it with something new.
Common pitfalls
- Adding images, animations or colours "to make it interesting" without asking whether they help the idea.
- Reading a dense slide aloud, so students process the same words twice and miss the point.
- Teaching every piece at once because the syllabus is long, instead of sequencing.
- Keeping heavy step-by-step support for students who already no longer need it.
Redesign an Overloaded Slide
Your facilitator will guide you through this activity in the session.
Reflect
- What was the easiest source of extraneous load to spot? The hardest?
- What's one habit in your own materials that's likely adding extraneous load without you noticing?
- How would you explain "germane load" to a colleague in one sentence?
Try it tomorrow
- Take one slide or worksheet you use next week and delete half of its words and every purely decorative picture.
- Put labels directly on a diagram instead of in a separate legend or caption.
- Give one worked example, one half-completed example and one independent problem on the same skill, and see who needs which.
Further reading and links
You can't make working memory bigger. You can only make what competes for it smaller — cut extraneous load so students have capacity left for the load that actually teaches them something.