We use the first three activities in rapid succession, to emphasize to students the geometric nature of flux. These make a nice stand-alone introduction to the geometry of flux or they can be used as a warm up for a final activity–using Gauss's law to find the electric field in situations with high symmetry. (The second activity is long and can be omitted if students will not be expected to calculate flux on complicated surfaces.)

• Concept of Flux: A kinesthetic activity in which students use rulers to represent a vector field and a hula hoop to represent a surface. The class discussion focuses conceptually on what contributes to the flux.
• Calculating Flux: A small group activity in which students calculate the flux of a simple but non-constant vector field through a cone.
• Visualizing Flux:A Maple/Mathematica activity that allows students to explore the flux of the electric field through a cubical surface due to a point charge. The position of the point charge can be varied so that there are different amounts of flux through each of the six surfaces. It is possible to move the point charge source outside of the cube, or even onto the surface of the cube.
• Gauss's Law: A compare and contrast activity in which students are asked to work in groups to find the electric field using Gauss's Law for either a spherically or cylindrically symmetric charge density. Students must make explicit symmetry arguments using Proof by Contradiction as part of their solution.