- Introduction: Dyscalculia in Physics
- Part1: Variables
- Part2: Using Bar-Models to show Conservation
- Part3: Using Bar-Models to Teach Rate Calculations
- Part4: Using the Area of a Rectangle to Model Relationships in Physics
Series: Inclusive Physics Teaching (Part 5 of 6) | Read time: 3 minutes
The Problem: Visualising the Physical Situation
When presented with a physics problem, physicists reach for a pencil. Diagrams help us think, but some diagrams help far more than others.
For dyscalculic learners and students with working memory limits, wordy paragraphs and realistic photos create severe cognitive friction. Diagrams that make it easier to search and recognise information—and reduce the amount of inference needed—dramatically reduce extraneous cognitive load.
Comparing Representations & Computational Efficiency
| Representation | Computational Efficiency & Cognitive Load |
|---|---|
| 1. Text Description “One end of a rope is secured to the floor while the other end is passed through a pulley directly above. The free end of the rope is attached to a 5 N weight. The weight is suspended by the rope.” | High Search & Inference Load: Text must be searched line by line to locate information.* Requires heavy working memory mental simulation to infer spatial positions, pulley arrangement, and force directions.* Presents high extraneous cognitive load before any calculations begin. |
2. Real Object or Photograph | High Noise (extraneous information): Real apparatus and photographs contain irrelevant visual detail (clamp stand, lab background, textures). This hides the underlying physics. Students need to isolate the physics from the noise. |
3. 3D Realistic Drawing | Reduced Spatial Inference and Shows Hidden Forces: This makes spatial arrangement easier to interpret, but still requires inference: the solver must mentally deduce that both ends of the rope exert equal downward forces balanced by the meter. The diagram does not explicitly show force vectors. |
4. 2D Physicist Sketch | Maximum Computational Efficiency: A 2D sketch is much simpler to search visually. Explicit arrows show force size and direction directly, reducing the need to hold them in working memory. Standardised symbols allow rapid recognition. Cognitive load is outsourced to the paper. Note: Sketch diagrams like these are a key tool for thinking hard in physics at all levels. Professors and Nobel prize winners sketch concepts to offload cognitive load to aid deeper thinking. |
How Diagrams Reduce Cognitive Load (Larkin & Simon, 1987)
- Search: Text requires line-by-line reading to build a mental spatial map. A clear diagram allows rapid spatial indexing and visual search.
- Recognition: Standardised, familiar formats allow rapid pattern matching rather than guesswork.
- Inference: A 2D physics sketch makes forces explicit with arrows, externalising calculations that would otherwise overload working memory.
Classroom Routine: Explicitly Teaching 2D Sketches
Teach students an explicit 3-step drawing routine:
- Strip Away Realism: Replace 3D apparatus drawings or photos with simple 2D shapes (circles, boxes, lines).
- Add Explicit Vectors: Draw relevant vector arrows.
- Label Spatially: Place magnitudes and units directly beside their corresponding arrows.
Takeaway
In physics, a diagram is not an artwork—it is an external working memory support. Teach students to sketch simple 2D diagrams with clear force arrows so the paper carries some of the cognitive load.
