Ask the students to draw on one side of their first disk a yellow lighting bolt outlined in black. On the opposite side, ask the students to draw a sky. Next ask the students to twirl their thaumatropes and then pull the strings tight. As the thaumatrope unwinds, the image will flip back and forth showing a lighting bolt in a sky. Other thaumatrope require that the image on one side is oriented upwards and the image on the opposite side is oriented downwards.
Students can experiment with different shapes.