Browsing by Author "Prather, Edward E."
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Item Applicability of the Newtonian Gravity Concept Inventory to Introductory College Physics Classes(2016-06) Williamson, Kathryn E.; Prather, Edward E.; Willoughby, Shannon D.The study described here extends the applicability of the Newtonian Gravity Concept Inventory (NGCI) to college algebra-based physics classes, beyond the general education astronomy courses for which it was originally developed. The four conceptual domains probed by the NGCI (Directionality, Force Law, Independence of Other Forces, and Threshold) are well suited for investigating students' reasoning about gravity in both populations, making the NGCI a highly versatile instrument. Classical test theory statistical analysis with physics student responses pre-instruction (N = 1,392) and post-instruction (N = 929) from eight colleges and universities across the United States indicate that the NGCI is composed of items with appropriate difficulty and discrimination and is reliable for this population. Also, expert review and student interviews support the NGCI's validity for the physics population. Emergent similarities and differences in how physics students reason about gravity compared to astronomy students are discussed, as well as future directions for analyzing the instrument's item parameters across both populations.Item Development of the Newtonian Gravity Concept Inventory(2013-12) Williamson, Kathryn E.; Willoughby, Shannon D.; Prather, Edward E.We introduce the Newtonian Gravity Concept Inventory (NGCI), a 26-item multiple-choice instrument to assess introductory general education college astronomy (“Astro 101”) student understanding of Newtonian gravity. This paper describes the development of the NGCI through four phases: Planning, Construction, Quantitative Analysis, and Validation. We discuss the evolution of the instrument through three versions, including the refinement of a set of four concept domains and nine examples of items to illustrate how expert review, student interviews, and Classical Test Theory statistics informed our approach. We conclude that the NGCI is a reliable and valid instrument.