You know --- just something to toss out there --- at least where medicine is concerned.
Something I find dreadfully saddening is most colleges of medicine needlessly complicate most of their studies currently, today. Some could make a claim that big pharma pushes that ideologue to make it easier for them to earn money, if you buy into that rational; less I digress.
There are certainly ways to enhance educational programs simply not being done today.
Just now, I think its a stretch suggesting calculus is easier to learn at younger ages, but if my example proves anything, it does illustrate fundamental shifts in how education is tackled can absolutely shift rate of learning.