1. Elementary school practices;Becker,1996
2. The open-ended approach: A new proposal for teaching mathematics;Becker,1997
3. Using puzzles: Problem-solving and abstraction;Cha,2007
4. The evolution of mathematical explorations in open-ended problem solving situations;Cifarelli,2005
5. A beginning teacher's view of problem solving;Cooney;Journal for Research in Mathematics Education,1985