1. Altieri, M. B., et al. (2008). California mathematics. Concepts, skills, and problem solving 4. Glencoe: McGraw-Hill.
2. Bastable, V., & Schifter, D. (2008). Classroom stories: Examples of elementary students engaged in early algebra. In J. Kaput, D. W. Carraher, & M. L. Blanton (Eds.), Algebra in the early grades (pp. 165–184). New York: Routledge.
3. Blanton, M., & Kaput, J. (2005). Characterizing a classroom practice that promotes algebraic reasoning. Journal for Research in Mathematics Education, 36(5), 412–446.
4. Blanton, M., Brizuela, B. M., Gardiner, A. M., Sawrey, K., & Newman-Owens, A. (2015). A learning trajectory in 6-year-olds' thinking about generalizing functional relationships. Journal for Research in Mathematics Education, 46(5), 511–558.
https://doi.org/10.5951/jresematheduc.46.5.0511
5. Blanton, M., Brizuela, B. M., Gardiner, A. M., Sawrey, K., & Newman-Owens, A. (2017). A progression in first-grade children’s thinking about variable and variable notation in functional relationships. Educational Studies in Mathematics, 95(2), 181–202.
https://doi.org/10.1007/s10649-016-9745-0