Khan Academy: Integral Calculus
Khan Academy

How do you find the area under a curve? What about the length of any curve? Is there a way to make sense out of the idea of adding infinitely many infinitely small things?

GeoGebra: Building Surfaces with Cross Sections and Function Modeling
GeoGebra

The Toblerone candy bar shown is an example prism. By definition, what exactly makes a 3D solid a prism? Describe.