VOLCANOES OF THE CONNECTICUT VALLEY: A STUDENT CENTERED, PHENOMENON-FOCUSED EXPLORATION OF EXTENSIONAL TECTONICS

Teaching K-12 geoscience topics through the lens of 3D standards necessitates significant shifts in instructional strategy. Achieving these shifts is not easy. However, the geosciences are well-suited to the phenomenon-focused approach intended for 3D standards due to the relative ease of identifying good anchor and investigative phenomena (good phenomena are content-appropriate, standards-aligned scientific observations that are relevant and compelling to students). The evidence of Mesozoic volcanism preserved in the Connecticut Valley of New England can anchor a middle school study of tectonics. We cast this anchor as an observation or a question (e.g., How do we know there were volcanoes in the Connecticut Valley during the Age of Dinosaurs?). The anchor unites a series of investigative phenomenon-focused activities where students apply practices and cross-cutting concepts to explore and explain the observations in question, thereby clarifying relevant core-idea content. For example, the French King Bridge crosses a Connecticut River gorge in Gill, MA. Rocks exposed at the eastern end of this bridge are gneisses dating to ~454 Ma; rocks at the same elevation on the western side are conglomerates dating to ~200 Ma. This first-in-sequence phenomenon focuses an activity whereby students analyze data to support an explanation (student actions here relate to the practices for MS-ESS2-3 and MS-ESS2-2, the 3D standards to which this phenomenon aligns). Students need to know a bit about gneiss and conglomerate to address the phenomenon, so nesting a rock identification activity within the bridge activity introduces the whole stratigraphic section for the Connecticut Valley Volcanoes experience at the outset. Upon explaining the bridge phenomenon (with a normal fault), students address the remaining phenomena in sequence, and in doing so learn that the relevant volcanic rocks are related to the same extensional events that produced the bridge phenomenon, and that the ages of these events associate the entire Connecticut Valley Mesozoic section with the initial opening of the Atlantic. Ultimately, students use explorations of a series of distinct, but related, occurrences to develop knowledge about extensional tectonics and the early breakup of Pangea.