Britannica ImageQuest offers students, teachers, and schools access to a huge media library encompassing over 3 million rights-cleared images that can be used to support teaching and to enhance students learning and engagement. These images are sourced from over 60 leading collections including Getty Images, Chicago History Museum, The Bridgeman Art Gallery, Universal Images Group, Natural History Museum, and more. Users can search for images by collection, keyword, image type and ratio.
ImageQuest also provides educational resources in the form of visual lessons and projects to be used in the classroom with students. These include Image Story which helps students learn how to use 'the powers of storytelling and imagery to inform others about a research topic'; Best in Search to help students develop strong search skills; Unit Wrap-up that teaches students how to use the communicative strength of imagery to create concise lesson-wrap-ups, among others.
Additionally, ImageQuest offers a free guidebook to help districts and schools learn what they can do avoid claims of copyright infringement and what they can do when they arise. If you want to teach your students about copyright and fair use, I would recommend Copyright Creative.
The materials provided by ImageQuest including their media library are not free. There are several subscription plans to choose from. Britannica ImageQuest was featured in the 2021's AASL list of the best digital tools for teaching and learning which is where I learned about it.