Creating timelines is free and easy. Check out the sites below. Some offer interactivity by allowing videos and other documents to be embedded.

is a free web-based timeline creation tool. Each timeline is a "topic." Add videos, photos, text, and choose from a variety of backgrounds. Sign up in order to be able to save your timeline creation. You can view the finished product as a timeline, a map, a flipbook, or a list. It allows you to embed the code from your finished timeline on your website.

is a free web-based timeline. Easily create and share timelines with pictures and videos.

You can create animated slideshow timelines with a beautiful array of features, including the ability to upload music. This one works well for digital storytelling also.

Timeline JS An open-source tool that enables you to build visually-rich interactive timelines and is available in 40 languages.
It can pull in media from different sources and has built in support for:

Twitter, Flickr, Google Maps, YouTube, Vimeo, Vine, Dailymotion, Wikipedia, SoundCloud and more media types are regularly added.
Since Google is enabled, students can collaborate on their timelines.