Application, Interactive, Visualization
I have recently added a new section to The Mathenaeum with activities designed to help understand differentiation and integration. The four activities currently provided allow easy visualisation and exploration of derivatives and integrals, and discuss how the formulas arise as limits of well known geometric ideas (the equation of a line for differentiaion, area of rectangles for integration). The integration activity also has a simple discussion of why differentiation and integration are opposites (The Fundamental Theorem of Calculus).
If you like these activities, please follow me on Twitter and help me increase the visibility of this and the other activities at The Mathenaeum.
8 February 2016 Edit: 4 February 2016
User submitted, thanks to Ken Wessen