1. First-year undergraduates' difficulties in working with different uses of variable / María Trigueros and Sonia Ursini
2. Cooperative learning in calculus reform: What have we learned? / Abbe Herzig and David Kung
3. Calculus reform and traditional students' use of calculus in an engineering mechanics course / Cheryl Roddick
4. Primary intuitions and instruction: The case of actual infinity / Pessia Tsamir
5. Student performance and attitudes in courses based on APOS theory and the ACE teaching cycle / Kirk Weller, Julie Clark, Ed Dubinsky, Sergio Loch, Michael McDonald and Robert Merkovsky
6. Models and theories of mathematical understanding: Comparing Pirie and Kieren's model of the growth of mathematical understanding and APOS theory / David Meel
7. The nature of learning in interactive technological environments: A proposal for a research agenda based on grounded theory / Jack Bookman and David Malone