Home made way to clean your Flat Iron! - "Turns out this was hardly even a challenge for the "miracle cleaner". :-) I made my usual paste of baking soda and hydrogen peroxide and started rubbing it in with my fingers. It immediately took all but the thickest parts of gunk off with hardly any effort at all."
let students paint paper with watercolors, wet on wet, similar colors. Let dry and cut into triangles. Students pick triangles and glue down randomly, leaving white around each one. Maybe try with black or other color background?