In the same spirit I would recommend that you try section 2.2.4[1] of the SICP textbook using The SICP Picture Language [2] which can be found here [3]. That s

In the same spirit I would recommend that you try section 2.2.4[1] of the SICP textbook using The SICP Picture Language [2] which can be found here [3]. That section is based on the same original paper, and it is very nice to check on the book's explanation using a modern environment such as DrScheme. [1] http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-15.html#%_sec_2.2.4 http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-15.html... [2] http://planet.plt-scheme.org/package-source/soegaard/sicp.plt/2/1/planet-docs/sicp-manual/index.html http://planet.plt-scheme.org/package-source/soegaard/sicp.pl... [3] http://planet.plt-scheme.org/display.ss?package=sicp.plt&owner=soegaard http://planet.plt-scheme.org/display.ss?package=sicp.plt&#38...