There are literally thousands of sites offering images. Here are some no-cost or low cost options to get you started.
Image Sources

Find Free and Fair Use Photos for School
Grabbing images from Google is easy. You search, copy and paste. It’s a no-brainer and often the first thing students do when creating any sort of digital project that requires images. But how do your students know if they have permission to use someone else’s photos? To be a good digital citizen and be in alignment with the ISTE's… learn more

Free to Use and Reuse - Library of Congress
The Library of Congress has a wide ranging set of digital collections that are free to use and reuse. Their digital collections comprise thousands (millions?) of items including books, newspapers, manuscripts, prints and photos, maps, musical scores, films, sound recordings and more. This link features sets of items from the Library's digital collection organized by… learn more

FreeImages
There are a number of hybrid sites like FreeImages.com that provide both free and for-purchase photos. With over 300,000 free photos, sites like this can provide interesting images for your student's projects. learn more

Freepik
Our goal is to offer the best high-quality content: illustrations, photos, icons, mockups, and presentations templates learn more

Google Images
Google image search can be used in a couple of ways. If you are unsure if an image is in the public domain, drag and drop the image file onto the Google Image search page. The image will be analyzed and matches are displayed. Go thru the list for matches to stock photography web sites.… learn more
Keep A Record!
It is highly recommended that you and your students keep a record of the source every image and media item used in a project. If there is ever a question, you can show where the item was obtained and that a good faith effort was made to not violate copyright. learn more

Kid's Picture Search
A CHILD FRIENDLY SEARCH ENGINE AND PORTAL FOR YOUTHS KINDERGARTEN THROUGH ELEMENTARY. learn more

Library of Congress: Free to Use Teachers & Students
Free to Use and Reuse: Teachers & Students: This set illustrates the wide variety of school, home, and informal learning environments that brought teachers and students together from kindergarten through college and adult continuing education, primarily in the 20th century. The pictures are from the Prints & Photographs Division collections unless otherwise noted. learn more

NASA Images
NASA's image library consolidates imagery spread across 60 collections into one searchable location. Students can embed content in their own sites and choose from multiple resolutions, including the original size, to download. NASA images cover everything from space and spacecraft, to stunning pictures of the Earth and it's climate and people. Most of the images… learn more

Photo Editor Free Online: iPiccy
Photo Editor. Collage Maker. Graphic Designer Everything you need to make your photo awesome online learn more

Photos for Class
Teachers have told us they need a place to access safe images that are available to be used in the classroom and for educational purposes. Plus, they want accurate image citations. We’ve heard you and created “Photos For Class” to meet your needs for images! Age Appropriate Images - All images are appropriate for the school… learn more

Shutterstock
Stock photos can be a step up from the varying quality of free photos. For around $10 per image (varies by company), you can get a non-exclusive license to use quality images in you and your student's projects. Shutterstock is an example of this type of site. We've used a number of their images in… learn more

The Graphics Fairy
The Graphics Fairy has over 4,500 free vintage stock images, illustrations, old pictures, antique graphics, and vintage printables. DIY and craft tutorials are offered as well. All images on the site are assumed to be royalty free images that are in the public domain. learn more

Unsplash
Unsplash has over 2 million free high-resolution images "brought to you by the world's most generous community of photographers". Covers a wide variety of subjects with high quality images. learn more