We present the development, administration, and analysis of a focused inventory on the rotational
kinematics of a rigid body around a fixed axis. The inventory, which is made up of 13
multiple-choice questions, was developed on the basis of interactions with students and teachers.
The systematic and iterative aspects of the construction of the inventory are illustrated. The
questions, which were validated, were administered to a set of teachers ( N = 25) and two groups of
preuniversity students ( N = 74 and 905) in India. Students, as well as teachers, exhibited
difficulties in applying the operational definition of angular velocity to a rigid body. Many
erroneously assumed that an angular acceleration cannot exist without a net torque. Patterns of
reasoning resulting in errors were identified and categorized under four broad themes. These include
inappropriate extensions of familiar procedural practices, reasoning cued by primitive elements in
thought, lack of differ…