Cerebral Cortex: The Thinking Part of the Brain

The surface area of the cerebral cortex [All Ages]

Opening Questions

How big do you think the human cortex would be if you stretched it out?

How big would our heads have to be if it was smooth?


Play this videoclip to see the true surface area of the brain.

Discussion Points


Q: How big would the brain have to be if the cortex was smooth?

A: If the outer layer of the brain was completely smooth, the average brain would be about 88cm in circumference and our skull would have to be as big as a beachball!.


Q: Why do you think it matters if humans have heads smaller than beachballs?

A: Human babies have larger heads than many animals because they have such large brains. Women have bigger hips than men so that they can give birth to the baby’s big head. If the brain were smooth the head would have to be much, much bigger and so would women’s hips, which would make it difficult for them to walk or run, which would have been especially important when we were evolving.