Can you work out the dimensions of the three cubes?
Which of the following cubes can be made from these nets?
This article outlines the underlying axioms of spherical geometry giving a simple proof that the sum of the angles of a triangle on the surface of a unit sphere is equal to pi plus the area of the triangle.
It is not necessary to use a lot of algebra for representation where students are not sufficiently confident with that.
A spreadsheet that allows volume to vary is powerful but only after students have established an understanding of the calculation process being carried out by the computer on their behalf.