free software for students

I am looking for some free graph and chart software to help someone with their school work. I have seen this online

http://www.jfree.org/jfreechart/index.php

which is downloadable at soundforge. I don't really understand open source software, so would this be suitable for a 14 year old to use? If not does anyone have any other suggestions.

Open source software is just like any other software except that you can also get the source code for it.

But that is an "Java Class Library" which means it is a class library which you use when programming in Java.

So, that is not what you want. But I think it is possible todo charts with and graphs with OpenOffice.org

Thanks for that information Eldmannen.