Here's a few things I came up with:
Student Cognition: http://www.mste.uiuc.edu/courses/ci431kt/ci431fall98/issues/cognition/default.html
Curriculum Design: http://mathcurriculumcenter.org/research_framework.php
http://www.dataintheclassroom.org/content/view/3/3/
Teaching Methodology: http://www.crlt.umich.edu/tstrategies/teachings.php
http://jutlp.uow.edu.au/2005_v02_i02/pdf/barraket_004.pdf
The pages above list out either books used on research with topics, or present a number of ideas that could be used for research.