This silly app serves a serious purpose -- it helps students visualize key concepts of linear algebra and/or computer graphics:

* What is a matrix?
* What is a linear transformation?
* What is an affine transformation?

and optionally (i.e, only if enabled under settings):

* What is a determinant?

lastly, for advanced students. This is behind a setting, so students who don't need this can ignore it:

* What are Eigenvectors and Eigenvalues?