In this unit we learn about variation of line and the artist Bridget Riley among other optical illusion artists.
The students start with a contour line drawing and then practice different designs to try and fool the viewer and really make it difficult to see what their original picture is. I have a worksheet that I give my students with different designs because sometimes it gets overwhelming for them. The results usually come out well, as long as they don't scribble over everything in the process, ha ha.
We used Bristol paper and Micron Pens.My mentor turned me on to using Micron pens because when working on large areas doesn't show up streaky quite like a marker might leave. Even if you don't use these exact pens, because they can get pricey it still turns out nicely. I have used all types, just a preference.