I stumbled across Histography.io recently and was blown away by probably the most interactive timeline I have ever seen! The site is simple and truly elegant in the way it interacts with users. First, you can choose a epoch/era by clicking on the slider bar at the bottom of the screen (you can drag the edges of the slider bar to view a smaller or larger chunk of time), then you can click on a dot to uncover an event, figure in history. After clicking on the event, an image pops up with links to a video on the topic, a wikipedia page, and other related events or information. On the left side of the screen, you can click on different topics such as Literature, Wars, Politics, and more. Lastly, you can click on the small light green box in the top left corner to explore "Selected Events" deemed important to history by the website's authors (example events include the release of the of first motion picture, Einstein's development of the theory of relativity, the fall of the Berlin Wall, and many more).
From elementary to high school, this website can serve many purposes for teachers of almost every subject, not just social studies. It is free to use, so have your kids try it today- you'll get plenty of "ooo's" and "ahhh's". :-)