This is the second part of a broader investigation which explores the reasons behind the contextual
variations in student responses at a fine-grained level. In the previous article (John 2017 Eur. J.
Phys. 38 [http://dx.doi.org/10.1088/0143-0807/38/1/015701] 015701 ) it was established that the
students’ responses are highly context dependent at a fine-grained level. This article presents the
reason for the contextual variations of student responses from their free written responses. The
result indicates that students who are being triggered by the productive resources during the
engagement with the task will arrive at the correct (canonical) conclusion and those triggered by
the unproductive resources will arrive at an incorrect conclusion. We identified the productive
foothold ideas in a simple DC circuit with a single resistive element.