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Teachers’ Understanding of Algebraic Generalization

  • Author(s): Hawthorne, Casey Wayne
  • Advisor(s): Philipp, Randolph
  • et al.
Abstract

Generalization has been identified as a cornerstone of algebraic thinking (e.g., Lee, 1996; Sfard, 1995) and is at the center of a rich conceptualization of K–8 algebra (Kaput, 2008; Smith, 2003). Moreover, mathematics teachers are being encouraged to use figural-pattern generalizing tasks as a basis of student-centered instruction, whereby teachers respond to and build upon the ideas that arise from students’ explorations of these activities. Although more and more teachers are engaging their students in such generalizing tasks, little is known about teachers’ understanding of generalization and their understanding of students’ mathematical thinking in this domain.

In this work, I addressed this gap, exploring the understanding of algebraic generalization of 4 exemplary 8th–grade teachers from multiple perspectives. A significant feature of this investigation is an examination of teachers’ understanding of the generalization process, including the use of algebraic symbols. The research consisted of two phases. Phase I was an examination of the teachers’ understandings of the underlying quantities and quantitative relationships represented by algebraic notation. In Phase II, I observed the instruction of 2 of these teachers. Using the lens of professional noticing of students’ mathematical thinking, I explored the teachers’ enacted knowledge of algebraic generalization, characterizing how it supported them to effectively respond to the needs and queries of their students.

Results indicated that teachers predominantly see these figural patterns as enrichment activities, disconnected from course content. Furthermore, in my analysis, I identified conceptual difficulties teachers experienced when solving generalization tasks, in particular, connecting multiple symbolic representations with the quantities in the figures. Moreover, while the teachers strived to overcome the challenges of connecting different representations, they invoked both productive and unproductive conceptualizations of the symbols. Finally, by comparing two teachers’ understandings of student thinking in the classroom, I developed an instructional trajectory to describe steps along students’ generalization processes. This emergent framework serves as an instructional tool for teachers' use in identifying significant connections in supporting students to develop understanding of algebraic symbols as representations that communicate the quantities perceived in the figure.

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