Last night I posted a video demonstration of how to create a timeline through Read Write Think's timeline creator. That is an excellent tool, but at the high school level it might be a bit too simple. Here are some other good timeline creation tools.
Timeline JS is an open source timeline creation tool. Timeline JS supports inclusion of image and videos in the events on the timelines that you create. To create a timeline through Timeline JS you first create a Google Spreadsheet with this template. After creating the spreadsheet you publish it to the web and insert its URL into the Timeline JS generator. The last step is grabbing the embed code from Timeline JS and embedding your timeline into your blog or website. Watch the video here to learn more.
myHistro is a timeline builder and map creation tool rolled into one nice package. On myHistro you can build a personal timeline or build a timeline about a theme or event in history. Each event that you place on your timeline can be geolocated using Google Maps. myHistro timelines can be created online or you can use the free myHistro iPad app to create events on your timeline.
TimeGlider offers some nice layout options. The layout option that I like best in TimeGlider is the ability to stagger or indent events below each other in a sequence. TimeGlider also makes it easy to display the relative importance of an event by increasing its size in comparison to other events on the timeline. TimeGlider accepts dates in A.D./B.C. format.
Dipity is a great timeline creation tool that allows users to incorporate text, images, and videos into each entry on their timeline. Like most good web tools, Dipity has a collaboration option and has multiple options for sharing your timelines publicly or privately. Each entry to a Dipity timeline can include multiple types of media which allows users to add more detail and information than can be included in a traditional timeline. If you want to import Tweets and other social media messages, you can do that too on Dipity. Dipity will work on your iPad. Dipity went offline for a few days earlier this fall and then reappeared without explanation. If it wasn't for that hiccup, I would have put it at the top of this list.