Using Pixlr

Pixlr (www.pixlr.com) is a robust image manipulation tool that runs completely through your web browser, offering a free online alternative to Photoshop. 

source: Wikimedia Commons (Creative Commons attribution license)

The collage above was made entirely within Pixlr. I started with an original image from Wikimedia Commons and used Pixlr's online tools to add text, modify colors, isolate certain elements, change the contrast and brightness of the image, and arrange them into a collage.

Pixlr can be a helpful tool for students to have access to in the classroom.