TEACHING AND ASSESSING THE NGSS SCIENTIFIC PRACTICE OF MODELING: A CASE STUDY USING PHYSICAL MODELS IN EARTH SCIENCE

Teaching and assessing the “Practices of Science & Engineering” is one of the most challenging aspects of the Next Generation Science Standards. For the past 4 years, we have been working with New York State Regents Earth Science teachers and their students on the practice of “Developing and Using Models” using physical models, including models of the sun/moon/Earth system and depositional systems. We observe that many Earth Science teachers tend not to consider teaching about models and modeling per se to be part of their responsibility; rather the models are seen as a vehicle for teaching about Earth phenomena that cannot be directly experienced in the classroom. Drawing on the theory of analog structural mapping, we have unpacked the elements of what it means for students to understand a physical model, and developed an assessment that probes their understanding of the correspondences and non-correspondences between model and Earth System. The assessment distinguishes between Earth-model mapping at the level of entities/attributes (e.g. basketball corresponds to Earth), motion/configuration (e.g. small ball moves around big ball like moon moves around Earth), and causality/mechanism (e.g. doll on the big ball “sees” only part of the illuminated half of the small ball like a person sees phases of the moon.) The mean proficiency of students in our test population of 8^th and 9^th graders falls within the middle tier, meaning that they can answer most questions about mapping at the level of entities/attributes but struggle with questions at the level of mechanism/causality. We have developed three strategies by which teachers can help students towards a stronger mastery of models: have students explicitly discuss mapping between model and Earth system, use models to figure out questions for which they don’t already know the answer, and use models to interpret data. Finally, we note that typical classroom use of physical and computational models as a pedagogical proxy for an inaccessible portion of the Earth system fails to convey and may even obscure the scientists’ use of models as a statement of a hypothesis to be tested against observation. We suggest an instructional sequence that could help students understand how scientists use models to generate new knowledge as opposed to merely communicating old knowledge.