We identified modeling practices during whole class discussions of electricity concepts in the classes of two exemplary high school teachers. Four major model construction practices were shared between the teacher and the students referring to observations (O), and generating (G), evaluating (E), and modifying (M) explanatory models. Both groups achieved similarly impressive gain differences over a control group, and high rates of student contributions to modeling, indicating it is possible to achieve the latter. The teachers exhibited substantially different frequencies of scaffolding the practices. We conclude teachers may vary in their level of scaffolding but still experience equally strong student participation in modeling and gains in conceptual understanding. Importantly though, both teachers were focused on fostering the four modeling practices. We provide micro-analyses of classroom transcripts and representative diagrams to illustrate their process of teacher-student co-construction.