PIXEL: INVESTIGATING STUDENTS’ CONCEPTS OF PIXELS AND SENSE OF SCALE IN THE FIELD

Empirical work supports the claim that a high level of spatial thinking is critical to success in the geosciences. Spatial thinking includes many sub-skills such as mentally rotating an object, imagining the inside of a 3D object, and disembedding patterns from background noise. Here we focus on sense of scale, which refers to how an individual quantifies space and may develop through kinesthetic experiences. Sense of scale is important in many areas of the geosciences, including understanding remotely sensed imagery.

In this exploratory study, students (N=17, 59% female, 59% white, age 19-29) attending the Juneau Icefield Research Program completed a 3-hour, field-based activity designed to develop sense of scale and conceptions of pixels in remotely sensed imagery. Prior to the activity, students heard an introductory remote sensing lecture and completed both an open-ended pixel concept survey and the Sense of Scale inventory. Students then walked and/or skied the perimeter of several pixel types, including a 1 m x 1 m square (a WorldView pixel), a 30 m x 30 m square (Landsat) and a 500 m x 500 m square (MODIS). The group took reflectance measurements using a field radiometer as they physically traced out the pixel. The exercise took place in one area with homogenous reflectance, and a second with heterogeneous reflectance. After the exercise, students completed the pixel concept survey and a demographic survey.

Prior to the activity, most students could define a pixel as a tiny square representative of the “real world.” They held highly variable ideas about the scale of pixels in physical space, ranging from 1 mm to the size of the United States. A few students were aware that resolution affected the size of features that could be recognized within an individual pixel, but none were aware that reflectance also had an impact. Following the activity, students could correctly identify the scale of pixels in physical space and describe resolution, but still did not understand that reflectance impacted resolution. All students were able to correctly identify the scale of everyday objects within an order of magnitude. This project may guide future work investigating how field-based activities could be effective in teaching sense of scale.