This is a one page activity sheet for the Mystery Picture Project. Students investigate markers using a red filter (you must make the filters using red cellophane found at most party stores) to find which colors disappear. Then they use the markers to draw a pictures that would only be visible when viewed through the filter. It is a great art lesson on color filtering, or as an introduction to advanced light spectrum topics. You could even use this as an English lesson on perception and deception.