Concept Maps: see good article<ref>[http://phobos.ramapo.edu/~vasishth/Learning_Outcomes/Segalas+-Conceptual_Maps+Engg_Students+Sustainability.pdf J. Segalàs, D. Ferrer-Balas and K.F. Mulder , 2008, Conceptual maps: measuring learning processes of engineering students concerning sustainable development]</ref>

[[file:Concept maps 3.gif|700px|center|thumb|The measure of complexity of connections between concepts before and after coureses taken in different subjects<ref>[http://phobos.ramapo.edu/~vasishth/Learning_Outcomes/Segalas+-Conceptual_Maps+Engg_Students+Sustainability.pdf J. Segalàs, D. Ferrer-Balas and K.F. Mulder , 2008, Conceptual maps: measuring learning processes of engineering students concerning sustainable development] p.304</ref>]]