In this activity (on page 1 of the PDF under SciGirls Activity: Earthquakes), learners will use a magnifier to carefully examine samples of sand from different locations. They record their observations regarding the different grain characteristics to formulate their own explanations of where the sand came from, why the grains are jagged or smooth, and how they may have been sorted. Relates to the linked video, DragonflyTV GPS: Earthquakes.