Spherical Coordinates (robphy)
This visualizes some important aspects of spherical coordinates,
that I would use when teaching physics majors.
Techniques for some of these constructions were inspired by
https://www.geogebra.org/m/W7tDfJP5
Constant surfaces in cartesian, cylindrical, and spherical coordinate systems
by Serdar OKUYUCU
and
https://www.geogebra.org/m/NQwe7K89
Electric Field for Multiple Point Charges in 3-D
by Dave Nero