Summary Build models of mountains from a contour map, then use sand and water to explore how water erodes mountain sides. Science content Earth/Space: Landforms, Erosion (3) Activities in this lesson Mountain contours / topography Erosion and Stream flow Procedure Build mountains using a contour map, to understand how their shapes are represented on maps. Discuss how mountain shapes are changed by water flow and erosion. Watch erosion in action with a demo of the sand and water erosion activity (or student groups can each have their own, but this adds quite a bit of time to the lesson). Wrap: Erosion by water, as well as ice and wind, slowly over thousands of years, changes the landscape. Maps need to change to reflect that. Grades taught Gr 2 Gr 3 Gr 4