Findings from this collection of studies suggest that while some PTs master
computational strategies that allow them to compare decimals, convert between bases, and
represent familiar decimals, others have difficulty. Sources of this difficulty seem to be in
building meaning for and interpreting decimal notation. Notations are designed to
represent different linear combinations of quantities using a system of units, yet
explorations of place-value systems in bases other than ten reveal that PTs attend to the
patterns in the base-ten notation rather than the quantities they are meant to represent.
For such students, since 0.1 and 0.01 are units in the base-ten system, 0.5 and 0.05 are
incorrectly assumed to be units in the base-five system. Research contains evidence that
use of the number line and area models to represent decimals were effective tools in
revealing overgeneralizations based on subunits of 10 used in non-base-ten systems. In
addition, these findings point to the importance of exploring units and relationships in
contexts where base ten is not used, such as time.