Discussion
Guided in part by Geary’s (2004) model of mathematics learning,
we designed a fraction intervention that (a) emphasized conceptual
over procedural knowledge and (b) attempted to compensate
for AR learners’ limitations in the domain-general abilities
that predict development of fraction competence. Our instructional
design to compensate for these limitations involved teaching students
efficient strategies for segmenting measurement interpretation
tasks, creating automaticity with fractional values in relation
to marker fractions (e.g., one-half), providing a structure to encourage
students to exercise attentive behavior and work hard, and
simplifying the language of explanations.
With respect to conceptual knowledge, our major focus was the
measurement interpretation, even though it is a less intuitive form
of fraction understanding than the part-whole interpretation and
presently plays a subordinate role in American schooling. We
centered on the measurement interpretation of a fraction because it
is deemed a key mechanism in explaining the development of
competence with fractions (Geary et al., 2008). Yet its causal role
has not been evaluated in the context of an experimental study. We
contrasted this intervention to the typical school program for
developing fraction knowledge at fourth grade, which distributed
its focus roughly comparably between conceptual and procedural
knowledge and assumed a dominant focus on part-whole interpretation.
We hypothesized that intervention students’ conceptual and
procedural outcomes would exceed control group outcomes and
that learning would be mediated by student improvement in understanding
of the measurement interpretation of fractions. We
found support for both hypotheses.