Have you thought about presenting difficult concepts in your courses with images accompanying your narration? Or asking your students to use visuals such as pictures, drawings, graphic organizers to present their understanding of concepts or ideas? There are many free online tools that can be used to create and modify images or visual presentations.
Fotor is an online photo editing tool. With this tool you can resize, crop, rotate a photo, a picture, adjust the lighting curve, brightness, contrast, add photo effects and do many more in a few clicks.
Another online photo editing tool is Pixlr. It is basically an online version of Photoshop.
Pencil Madness is a web-based sketching and drawing application with which you can create anything you can imagine.
Bubbl can be used to create colorful graphic organizers.
To create interactive infographics, try Infogr.