I am teaching linear algebra as part of an information retrieval course, which now occurs online. I have a Wacom tablet and free drawing software, sketchBook for artists, so can draw circles ellipses etc. I need better software to draw cartesian coordinate systems, which includes grids and is preferably aimed at teaching mathematics. Can you advise whether there is such a package out there? An internet search has not brought one up. I know and use Mathematica, but it may be a little overkill to go that route. Perhaps a combination of Wacom and Mathematica would work. If you have examples of your own teaching of linear algebra (e.g. eigenvalues, eigenvectors, similar matrices, spectral decomposition etc) I'd much appreciate tips on how to set it up best.