When including artwork in the classroom, whether it's clip art or photographs, it is important to make sure that the images you decide to use are not copyrighted. There are quite a number of sources that provide images for the use of teachers, you just have to remember to use them and not uncopyrighted sources. Here's a list of some useful resources that include photos that are not copyrighted.
http://openphoto.net
http://www.teacherfiles.com/clip_art.htm
http://www.theteachersguide.com/Freebies.html
http://www.awesomeclipartforeducators.com/
http://webtech.kennesaw.edu/jcheek3/graphics.htm
http://www.school-clip-art.com/
Make use of all that these websites have to offer, including clip art, backgounds, borders, sounds, and even photographs!
Clipart adds considerably to classroom presentions, student projects, worksheets, and send home information to parents.
There are also websites that give teachers ideas for arts and crafts. Here are some..
http://www.preschooleducation.com/art.shtml
http://www.amazingmoms.com/htm/kidsart.htm
http://www.squiglysplayhouse.com/ArtsAndCrafts/index.html
http://www.arts-crafts.com/
http://www.enchantedlearning.com/crafts/
http://familyfun.go.com/arts-and-crafts/