Development and validation of a Nano Size and Scale Instrument (NSSI)

The concepts of size and scale are fundamental to nanotechnology education but can be difficult for beginning undergraduate students to grasp. It is important to develop curricular interventions to increase students´ conceptual understanding of size and scale, before moving on to more advanced subject matter. The purpose of this paper is to present the initial steps in the development of the Nano Size and Scale Instrument (NSSI), an assessment of students´ understanding of size and scale. Ten items were developed for the NSSI. The NSSI was administered to 118 first year engineering students and studied using Classical Test Theory. Results suggest that six of the ten items show appropriate difficulty and discrimination. Five of the items were of moderate difficulty and students´ mean scores overall were low (4.97 out of 10), indicating that students in this study found size and scale concepts difficult. Potential modifications to the NSSI are discussed.