Have you heard about Pixabay? It's a great website for finding good, quality public domain photos. These can be used in iMovie projects, as trigger images for your Augmented reality projects, and more. You can create an account for easy downloading or students can enter the captcha code for each photo they download.
According to Pixabay's terms and conditions "You can copy, modify, distribute and use the images, even for commercial purposes, all without asking permission and without paying attribution. However, depicted content may still be protected by trademarks, publicity or privacy rights."
According to Pixabay's terms and conditions "You can copy, modify, distribute and use the images, even for commercial purposes, all without asking permission and without paying attribution. However, depicted content may still be protected by trademarks, publicity or privacy rights."