The U.S. National Gallery of Art hosts more than 25,000 images of famous and not-so-famous works of art. Nearly all of the images can be downloaded and re-used for free. NGA Images also allows you to register and create online collections of images. The collections are called lightboxes.
"SAMR, a model designed to help educators integrate technology into teaching and learning, was developed by Dr. Ruben Puentedura, Ph.D.. The model aims to enable teachers to design, develop, and integrate digital learning experiences that utilize technology to transform learning experiences to lead to high levels of achievement for students."