Homework. We all hate it. It's worse when it's off the internet. All of those trees are killed due to the internet and schoolboards. How do we stop the cutting down of trees? The World Wildlife Federation created a .wwf file that is immune to printing.
more at http://www.popsci.com/technology/article/2010-12/world-wildlife-federation-creates-unprintable-wwf-format-save-trees