This is a fun site that my 4th graders and 2nd graders both love. It can be used throughout elementary school to practice sentences, sequence of events, character development, interpreting illustrations, etc.
Storybird is a website that has collections of illustrations that you can use to create an online storybook.
For classroom use, you can create a teacher account and add your class. From there you can share storybirds you have created, create assignments for students, or just let students start creating. It is pretty easy to maneuver and the storybirds each student creates can be published to the online classroom library and emailed to share with family. Teacher and students can also post comments on each other's work which is a great teach piece for being respectful and kind online.
I love this website and I definitely think it can be used in various ways in the classroom!