1. Ashlock, R. B. (1982). Errorpatterns in computation. Columbus, OH: Merrill.
2. The Development of Counting Strategies for Single-Digit Addition
3. How and When Should Place-Value Concepts and Skills Be Taught?
4. Baroody, A. J. & Ginsburg, H. P. (1986). The relationship between initial meaningful and mechanical knowledge of arithmetic. In J. Hiebert (Ed.), Conceptual andprocedural knowledge: The case of mathematics (pp. 75-1 12). Hillsdale, NJ: Lawrence Erlbaum Associates, I n c
5. Modeling Operations and Algorithms