I am not giving 5 stars because of lack of proofs ! some topology i think is necessary to talk about calculus
Good in giving though-invoking concept and visualization of differentiation, chain rule, relative rate of change, as well as Newton's linear approximation.
These corresponding demo example are illustrative and help us understand the main idea and underlying metaphor of differential operator "D" and symbol df/dx.
In addition, the technique of domain change in differentiation by using exponent and logarithm and implicit differentiation is really powerful and useful.
