  Rate-based processes comprise an important set of scientific phenomena, as
well as an important part of the K12 science curricula. Electric current is one
such phenomenon, which is taught in various forms from 4th - 12th grades.
Research shows that students at all levels find electricity difficult to
understand, and the difficulties persist even after classroom instruction. In
this paper, we present a design-based research study and argue that interacting
with multi-agent-based computational models based on the microscopic theory of
electrical conduction, can enable 5th grade and 7th students to develop a deep
understanding of electric current as an emergent process of flow in terms of
its microscopic level entities and their attributes, by bootstrapping their
repertoire of intuitive knowledge. We present a particular design strategy -
representing electric current as a fictive and transient process of charge
accumulation, without falling in previously reported traps of the "source sink"
mental models - and show how this strategy was effectively implemented in the
computational model as well as in the learning activities performed by the
students. We identify the mental models that students developed through their
interactions with the model, and show that after their interactions, students
were able to provide correct, multi-level explanations of the behavior of
electric current in a resistive circuit.
