Khoury and Zazkis (1994) investigated PTs’ “concepts of invariance of fractional
number under different symbolic representation” (p. 203). This work explored the
students’ ability to reason in situations where the quantities were different, but the
representations were similar (“Is (0.2)three = (0.2)five ?” [p. 193]) and when the quantities
were the same and the representations were similar (“Is the number ‘one-half” in basethree equal to the number ‘one-half’ in base five?” [p. 193]). Sixty-three of the 100
elementary PTs correctly answered the first problem using place-value charts and
computations such as “(0.2)three = 2 × 1/3” to generate fractions in base ten they could
compare (p. 194). While these students provided correct answers, their reasoning during
interviews often revealed attention to place-value syntax rather than quantity value. Some
students overgeneralized reasoning derived from their experience with base-ten place-
value units to reason about values of the positions to the right of the radix point. The values
were identified as 1/5, 1/50, 1/500 (p. 195), a finding consistent with reasoning the
authors identified in their prior work (Zazkis & Khoury, 1993). Investigating one half in
different bases (“Is the number ‘one-half’ in base three equal to the number ‘one-half’ in
base five?” [p. 197]) was far more difficult for the students, with only 26% of elementary
PTs concluding the two representations for the second task referred to the same quantity.
Drawing from the computational strategies used by the students, the authors concluded
that PTs’ “knowledge of place value and rational numbers is more syntactical than
conceptual” (p. 203)
Khoury and Zazkis (1994) investigated PTs’ “concepts of invariance of fractional number under different symbolic representation” (p. 203). This work explored the students’ ability to reason in situations where the quantities were different, but the representations were similar (“Is (0.2)three = (0.2)five ?” [p. 193]) and when the quantities were the same and the representations were similar (“Is the number ‘one-half” in basethree equal to the number ‘one-half’ in base five?” [p. 193]). Sixty-three of the 100 elementary PTs correctly answered the first problem using place-value charts and computations such as “(0.2)three = 2 × 1/3” to generate fractions in base ten they could compare (p. 194). While these students provided correct answers, their reasoning during interviews often revealed attention to place-value syntax rather than quantity value. Some students overgeneralized reasoning derived from their experience with base-ten place-value units to reason about values of the positions to the right of the radix point. The values were identified as 1/5, 1/50, 1/500 (p. 195), a finding consistent with reasoning the authors identified in their prior work (Zazkis & Khoury, 1993). Investigating one half in different bases (“Is the number ‘one-half’ in base three equal to the number ‘one-half’ in base five?” [p. 197]) was far more difficult for the students, with only 26% of elementary PTs concluding the two representations for the second task referred to the same quantity.
Drawing from the computational strategies used by the students, the authors concluded
that PTs’ “knowledge of place value and rational numbers is more syntactical than
conceptual” (p. 203)
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