SketchToy

As a web based drawing tool, SketchToy allows students and teachers to quickly create and share drawings. It is different than other drawing tools because it automatically converts the drawings into animations that can be shared with a link. Anyone who access your drawing can then add to it which creates a new link to share. This allows your students to quickly add to each others' drawings without needing an account.

SketchToy allows you to rotate your drawings as 3D models and includes a "vibration" setting which makes your drawings appear animated, but that would not be the reason to use SketchToy. You can also drag any image from your desktop onto the screen and add it to your drawing.

Because of the fast learning curve, SketchToy could be a great prototyping or quick illustration tool. Students could use it similar to other whiteboard apps and illustrate a poem, draw out a math problem or use it as a graphing tool. Throw in a screencasting app like Screencastify or SnagIt, and students could use it to talk about their learning as well or teachers could use it to create a flipped or blended classroom experience.