I do not really learn a concept until I can visualize it somehow. Indeed, when I was learning derivatives, it did not click until I saw a graph with a tangent l

I do not really learn a concept until I can visualize it somehow. Indeed, when I was learning derivatives, it did not click until I saw a graph with a tangent line. But everybody is not the same way. Some people prefer to develop their intuition based on a text explanation, some people need an example with numbers, some other people need an actual person to explain it to them in spoken words. When you learn better with one of these methods, seeing another one first may confuse you instead of helping. Moreover, once you have understand the concept, other kinds of explanations tend to broaden your view of the topic. I think this a great non-visual explanation of derivatives. No more, but no less. I think it has a great pedagogical value, even if it is not the best introduction for my way of learning.