We put together a special "Back to school" selection of images: http://office.microsoft.com/en-us/clipart/HA102379141033.aspx . There are lots of images to pick from, for teachers and students alike. Check it out!

WMF is a very versatile format: it is vector-based , which means images resize without any loss of quality - you can blow them up to the size of a billboard if you want to you can separate it into layers , and change its colors you can use...