Here are a few concept maps from previous students:
http://www.math-joey.blogspot.ca/2012/03/my-independent-assignment-session-6.html
http://kkailyg.blogspot.ca/2012/04/ia-concept-map.html
For this one look at the second post to see the concept map: http://kiddmath.blogspot.ca/
http://katsbrainseepage.blogspot.ca/2012/03/more-then-one-infinity-o0.html