Sprint Burn-down graphs were created by Jeff Sutherland from ideas that he had while flying reconnisance over North Vietnam. The two may seem to be totally different but Jeff does a great job of explaining the analogy inthis YouTube video:
The are several different ways of constructing the a Sprint burn-down; the original way (as documented by Ken in “Agile Software Development with Scrum”), was to plot the total number of hours remaining on a daily basis. It’s very common to now have teams plot the total number of tasks remaining and more advanced teams will plot the total number of stories remaining. All these approaches work just fine.
When working with a team I like to draw the sprint turndown graph by hand. This is often much quicker and easier than using Excel or other tool. If you spending more than two minutes a day praying this graph you’re doing it wrong.
Here’s an overview of the Sprint Burndown graph: