Geoboard

Press a button and drag the mouse to create vertices and the sides of a square grid shape. To delete a node, check the "Delete nodes" and then click on undesirable nodes. Check back the "Draw nodes" box when finished.

At present, among all browsers, only Firefox displays Java applet and that after issuing a warning and asking for confirmation. If that is too much for you, you can download the applet converted into an application that does not run in browser. You'll still need a Java installation, visit Sun's website at https://www.java.com/en/download/index.jsp, download and install Java VM.

(Instead of the applet you can download and run locally an application that is performing exactly the same job.)

Explanation

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