Recently, I was working with some educators who didn't know a pie chart from a hole in the ground. It was actually worse than that, but as we see more and more information communicated via charts, graphs, and other data visualizations, there is also a corresponding literacy needed to read and write these. And while my internal monologue may run along the lines of "OMG...you can't interpret a bar graph?!", my overall goal is to make data viz accessible to educators. Sometimes, that means I will have to start at the beginning.
But fret not if you don't know a bar chart from a scatter plot---let alone when to use one. Tuck a copy of the Choosing a Good Chart diagram in your back pocket and you'll be ready for action.
Extreme Presentation Method blog, the chart is available in several languages. What I like about this tool is that it starts with "What would you like to show?" The purpose of the communication is front and center. This can really guide the thinking of beginners. Even if they're not familiar with all of the charts they see on the page, it's a way to broaden their view beyond pie charts and line graphs.
For a more interactive way to select a chart, try the Chart Chooser over at Juice Analytics.