The Most Important Thing to Understand About Building Educational Knowledge Graphs

It’s subtle, but if you don’t understand it, you’re doomed to failure. You’ll build a system that students can’t learn from.

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This is the most important thing to understand about building educational knowledge graphs.

It’s subtle, but if you don’t understand it, you’re doomed to failure. You’ll build a system that students can’t learn from.

“When architecting a knowledge graph, think of each node/topic/lesson as a traffic intersection. You don’t want too many roads coming into a single intersection. Otherwise it’s a mess. It causes cognitive congestion.

Driving through a 5-point intersection, that’s a pain. Beyond 3-4 direct prerequisites is when the spidey senses start tingling.

But the best indicator is this thing called “key prerequisites”. Each lesson is broken down into a sequence of typically 3-4 progressively harder stages called “knowledge points”, and each knowledge point is linked to key prerequisites that are needed specifically for that knowledge point. Key prerequisites cover not only direct prerequisites but can also reach several steps back in the knowledge graph, maybe more.

When those start stacking up, when every single knowledge point needs like 3-4 key prerequisites, that’s when you worry about cognitive overload. The knowledge points, the key prerequisites, are where the pressure points are as the student moves through the lesson one stage at a time.

These heuristics about the limit being 3-4 direct prerequisites for a lesson overall, 3-4 key prerequisites at each knowledge point – they come from hard-won experience, emotional scar tissue of successes and failures – but it also turns out that when you look at working memory literature, you find that people can typically hold about 4 chunks of information in working memory. That’s about your capacity.”

(weaving together snippets from our discussion ~0:00-3:00)

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