Usually, I'm the type of person who does a google image search and copies and pastes images into my SmartBoard files. However, I'm hesitant to do that when I'm making foldables or graphic organizers since I know I'll be posting the files for others to download here on my blog. I hate it when others take credit for my work without acknowledging me, and I don't want to do the same to others by using their images in my files.
So, I was super excited when I found the ClipArt ETC site from the Education Technology Clearinghouse. The site currently features 66,902 pieces of free educational clipart. The site license allows you to use up to 50 images in any non-commercial project without asking for permission. I can't think of any time I've ever used anywhere close to 50 pieces of clipart in a project, so I never have to worry about asking for permission.
Plus, the clipart is super high quality. And, each image comes in three different sizes. Here's the direct link to the math clipart section.
My most frequently used clipart pages:
Blank Trigonometry Grids - These have saved mine and my students' sanity this year!!!
If I taught geometry, I would definitely be using the angles, geometric shapes, geometric solids, lines, and planes pages all of the time!
Hope you find something you can use with your students! There are lots of clipart for other subjects too on the site. But, I'm a bit partial to the math section. I have used clipart from other sections on grad school assignments, though.