That looks overall neat, though i'm not sure if i like the "." as a subroutine terminator - "end" would be better IMO. Also if this is meant to be used for teaching kids programming i'm not sure if the gambling bits in the Monte Carlo section would be appreciated by everyone :-P.<p>I really do like the trace mode though (but i'd make the variable display a bit more prominent, like on a grid or something and perhaps making the variables that are changed as red with a quick fadeout to black - pulse-like - to show what exactly was changed for that step).<p>Also, this is me, but i'd really prefer it if it was a small redistributable desktop application, QBasic-style :-P.