Visual Thought™ - A Free Mapping and Diagramming Tool
Visual Thought™ is actually "Freeware" rather than an Open Source program. (The difference is in the wording of the license).
Classroom Toolkit is reviewing this program to coincide with our book review of Mapping Inner Space in this issue.
The practical difference between an Open Source program and this freeware program is that you can download and use the Visual Thought™ program without cost for only the next 13 years. After 13 years, the license will run out and you will have to uninstall it...but in the meantime, you can use a mapping, diagramming and flow-chart making program for free.
Look at what this program can do...

Even more amazing, the objects that you create with the program can be connected with "Smart Connectors." Smart connectors are lines that stay connected, even when you move the object around on the screen.
How to Get this Program
Link to download the Visual Thought™ program.
Link to download the Visual Thought™ documentation.
What Else Do you Need to Know
Because the Visual Thought™ program requires a license key, you have to enter one after you install the program.
But, installing the license key is done with a separate program, not through the Help Menu.
When you start the Visual Thought™ program through the Program Files menu, start the Admin applet, instead.

Then, enter the following key in the rectangular block...

License Key to enter: 0356 9674 3262 8895 9914 96
That's it.
Now you and your students can use the Visual Thought™ program to diagram all sorts of documents, presentation, Web pages, notes and drawings.
You will find multiple uses for this program, particularly when you capture portions of the drawing on screen with a screen capture utility program. The power of the Visual Thought™ program is in its rapid drawing and editing capacity.
For a listing of free screen snapshot programs, visit, Ask.Com's free Screen Capture directory.
Happy Snapping!