Allows the user to see a number of binary tree variants, including the BST and AVL trees. Users don’t just watch a visualization, they can also interact by indicating where they believe the next node should be inserted, etc. Note: URL above is for Version 2.0. Version 1.0 can be found at [http://www.iu.hio.no/~ulfu/AlgDat/applet/binarytreesome/]

Strengths: Clear presentation of the content. Students are not just passive observers, but can show their knowledge by selecting where the next action should take place.

This is a Java applet, so just clicking on the link should bring it up in the web browser. After selecting a tree from the menu item, you can "queue up" a series of numbers in the text box. Then, one by one, the next number is presented in the upper left corner. Each number should be dragged to the appropriate spot in the tree. Initially, you just see a little ball in the upper left corner, and an open circle in the upper right/middle of the pane. Drag the green ball on the left to the open (white) circle. If you run out of numbers "queued up" then just type in some more. There are reports of problems with running this applet on the Mac.