How can we enhance the understanding of abstract mathematical principles in
elementary school? Different studies found out that nonsymbolic estimation could
foster subsequent exact number processing and simple arithmetic. Taking the
commutativity principle as a test case, we investigated if the approximate
calculation of symbolic commutative quantities can also alter the access to
procedural and conceptual knowledge of a more abstract arithmetic principle.
Experiment 1 tested first graders who had not been instructed about
commutativity in school yet. Approximate calculation with symbolic quantities
positively influenced the use of commutativity-based shortcuts in formal
arithmetic. We replicated this finding with older first graders (Experiment 2) and third graders (Experiment 3). Despite the positive
effect of approximation on the spontaneous application of commutativity-based
shortcuts in arithmetic problems, we found no comparable impact on the
application of conceptual knowledge of the commutativity principle. Overall, our
results show that the usage of a specific arithmetic principle can benefit from
approximation. However, the findings also suggest that the correct use of
certain procedures does not always imply conceptual understanding. Rather, the
conceptual understanding of commutativity seems to lag behind procedural
proficiency during elementary school.