I have been looking at Rotational Symmetry with year 7 and I was surprised at how much my high attaining students struggled with describing the symmetry of a given shape.
I created a task where students had to colour blue and red squares so that the rotational symmetry was either order 4 or 2. Students started with the grid of 3 by 3 and they completed that task but we talked about why some were possible and other weren’t and how you could know. Also, we discussed that if we had a solution for 2 squares then 7 was possible and the same for 3/6 and 4/5.