Dodecahedron and its Side Length LessonLevel 1 (suitable for all)The 16 most Important Geometric Objects: Overview with Formulas and Properties Illustrated overview of all geometric solids with important properties as well as formulas for areas, volumes and other quantities.
Ellipsoid with Shown Semi-Axes FormulaEllipsoid (Volume, Semi-Axis) $$ V ~=~ \frac{4\pi}{3} \, a \, b \, c $$
Parallelogram with Side Lengths and Height FormulaParallelogram (Area, Side Length) $$ A ~=~ \class{blue}{a} \, \class{red}{h} $$
Video Level 2 (without higher mathematics)Difference Between Partial and Total Derivative Here you will learn by example what the difference is between the partial derivative and the total derivative.
Divergence theorem Mathematical proof Level 3 (with higher mathematics)First and Second Green's Identity Proof of the two Green's identities (formulas) using the Gauss integral theorem, which are useful in the calculation of some electric potentials.
Video Level 4 (for physics pros)Fourier Series. An Intuitive Explanation. In this video you will learn what Fourier series / coefficients are and how to specify / calculate them for a function.
Arc Length, Angle and Radius of a Circle FormulaAngle Definition (Arc Length, Radius) $$ \varphi ~=~ \frac{ \class{red}{s} }{r} $$
Sawtooth Function Approximated by Two Different Fourier Series LessonLevel 3 (with higher mathematics)Fourier Series (+ Coefficients) and How to Intuitively Understand it Here you will learn what a Fourier series is, how it can be calculated, and the role of Fourier coefficients and basis functions.