This is another free photo repository that can be used for educational purposes. This has many good resolution photos in several different categories. It has categories that you can click around and find photos or you can type in the search field. I would recommend this one for science or social studies for all grade levels. There are images from animals and bugs to government buildings to objects and plants and trees. This has a wide variety of topics

This is a website that has lots of pictures really mainly for something like social studies. It is another website based on the creative commons license so they are free and can be used for education. In exploring this website you really have to have in mind what topic you are looking for images in because just clicking around didn't help but typing a subject in the search provided me with many images related to my topic/search. I would recommend this for maybe middle school or high school social studies or history teachers.

This is a website that has photos and 3-D drawings. These photos are free stock photos, backgrounds, and textures. On the website it does state that, "All our images are provided under a creative commons attribution license. This license lets you remix, tweak, and build upon our work, even commercially, as long as you credit pixelperfectdigital.com for the original creation." I thought this was unique because it is the first thing you see when you get to the home page. When you click on galleries you get many categories to choose from to find photos that you need. I think that any audience can use this. It does not matter what grade level. I think a teacher may need to use this to get images for any educational purpose. Once you click on a picture you are able to see details about the photo and have the option to download it.