Continued observation of teachers within the University of Maine Physical Sciences Partnership showed persistence over many iterations of professional development (PD) the use of an inconsistent model of accelerated motion. This model identified acceleration in the same direction as velocity as positive (speeding up is defined as positive acceleration) and acceleration opposed to velocity as negative; we will call this the speed model. We found use of this model in middle school physical science teachers in a survey and through interviews. A PD activity was also observed to study the teachers’ use of vectors and coordinate systems to solve kinematics problems. The “speed model” is used in place of the coordinate-based formalism of physics – termed the “direction model” in this paper – even though the speed model is insufficient to describe all physical situations. After careful identification of teacher resources, we see that they have the mathematical skills, and ability to use vectors within a coordinate system, which should allow them to arrive at the direction model; however, when faced with acceleration questions, many revert to using the speed model. The speed model may come from minus sign confusion in calculating changes in velocity, or it may be a velocity-dependent coordinate system; either way its persistence in the teacher population needs to be addressed.
Tabachnick, Elijah, "An Analysis of Middle School Physical Science Teachers' Understanding of Accelerated Motion" (2017). Honors College. 259.