Hierarchical classification of Quadrilaterals

[Michael de Villiers]

Some here might be interested in my interactive, dynamic, hierarchical classification of quadrilaterals which has been updated on my website. It includes links to some relations publications, including a suggested learning activity, using the animation features of dynamic geometry, to possibly help young learners to visually form class inclusions when they are first introduced to the various quadrilateral concepts. Go to: http://dynamicmathematicslearning.com/quad-tree-new-web.html