I don't know if this has already been suggested, but I have recently learned the programming language R, and it seems that it's exactly what you would like to use to teach your kids how to use a computer:
(a) it's free and available for _all_ systems [M$, Linux, Mac] (b) it's simple to use (c) it's powerful enough to treat numerical data For example, if you want to show the plot of a point, you just start R and type: plot(10, 10) and it plots a small ball at coordinates (10,10). If you want then to add another point, just type: points(12, 12) and the plot will be updated, showing the two balls. [notice that the first plot fixes the size of the graphic window, so points will only show points inside the picture]. Of course, rtfm and you will see that _much_ more can be done - it took me 1 hour to learn how to implement the visualization of the theorem of the eight points and the cubics ["given 8 random points in the plane, there is a 9th point such that every cubic that passes through the 8 must pass through the 9th"], based on a previous program I had written for Matlab/Octave. The Wikipedia entry for R is under "GNU-S" :-) Alberto Monteiro _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
