This activity provides students with an online simulation tool that can be easily used to visualize the cross sections of various cones, cylinders, prisms, and pyramids. This is the intersection of the sliced plane and the 3-D object. This is helpful for students of the Calculus III course because they have to visualize the shapes of cones, prisms, pyramids, and cylinders in order to find the cross-sectional area or volume. Cross sections can be difficult for students to understand, given that the concept requires that students switch between three-dimensional shapes and two-dimensional representations of those shapes. While this applet was designed to help students create and visualize cross sections of different solids, some students may also benefit from hands-on activities where they can physically slice open various solids before attempting more abstract explorations such as this applet.