*42%*:**Students' difficulties with unit vectors and scalar multiplication of a vector***41%*:**Vector Addition: Effect of the Context and Position of the Vectors***40%*:**The impact of students' epistemological framing on a task requiring representational consistency***39%*:**Modular Approach to Physics: Vector Addition - Tip-to-Tail Method***39%*:**Modular Approach to Physics: Vector Addition - Parallelogram Method***39%*:**Modular Approach to Physics: Addition of Three Vectors - Tip-to-Tail Method***39%*:**Students’ Responses to Different Representations of a Vector Addition Question***37%*:**Modular Approach to Physics: Vector Addition Practice - Three Vectors***37%*:**The Physics Classroom: Mechanics: Vectors and Forces in 2-D Problems***35%*:**2-D Vector Field Simulation***34%*:**Student Learning In Upper-Level Thermal Physics: Comparisons And Contrasts With Students In Introductory Courses***34%*:**Using time-on-task measurements to understand student performance in a physics class: A four-year study***33%*:**"After I gave students their prior knowledge" Pre-service teachers' conceptions of student prior knowledge***33%*:**Boston University Physics Applets: Vector Addition - Component Method***33%*:**A Study of Peer Instruction Methods with High School Physics Students***33%*:**Writing Position Vectors in 3-d Space: A Student Difficulty With Spherical Unit Vectors in Intermediate E&M***32%*:**Testing Students’ Understanding of Vector Concepts***32%*:**Algebra-Based Students & Vectors: Assessing Physical Understanding in Arrow vs ijk**