Over the years I’ve found that drawings and pictures can be good creative writing prompts for students. Here are two tools that elementary school students can use to create stories prompted by drawings.

Storybird provides templates and artwork for creating digital stories. To use Storybird
you simply select a theme (layout) then drag and drop the drawings you
like into your story. Once you’ve selected drawings for your story, you
then write in the text of your story. Using Storybird, anyone can create
great-looking digital picture book stories regardless of your drawing
skills or lack there-of.

Picture Book Maker allows students to create six page stories by
dragging background scenes into a page, dragging in animals and props,
and typing text. All of the elements can be sized an positioned to fit
the pages. Text is limited to roughly two lines per page. Completed
stories are displayed with simple page turning effects. Stories created
on Picture Book Maker can be printed.