If you are looking for a bank of images that you can use in the classroom for presentations and student work, then these two websites provide a whole host of images that are free to download and use without any copyright infringement, which will be a welcome relief to teachers!
Pixabay overs over 2.6 million high quality images, videos and music. All of the images come in a range of sizes and styles and you will be sur to find something that you like!
Unsplash is a similar website and hosts a whole bank of images provided by artists who wish to share their work. You can download the images in a range of sizes and search by category or keyword.