Students loved this drawing project! We created a grid on our papers and added two or three geometric shapes on top of the grid. Next, we mapped out where to put the color because we are not coloring every other "square" any longer but every other "space". For some, this was tricky, for others, they got the hang of it right away. When the color patterns are filled in, the shapes blend in with the grid, playing "tricks" with your eye, and this makes it an optical illusion.