I did an idle webcrawl through some old #riscos archives, and found a neat app that works on RO5 on the Pi! (anymode may be needed)

It's a little math program for algebra/geometry/calculus.

I remember a program like this (for cga pc) being used in my high school geometry class.

http://www.drobe.co.uk/archives//ftp.mirror.ac.uk/collections/hensa-micros/local/riscos/maths/a040.arc