This page illustrates tree structures - it toggles between a binary sorted tree and an expression tree.
For binary tree: the string is a series of 3 letter name/words which you can change.
Expression trees should be numbers or variables and operators + - * or / separated by spaces. eg 3 + 4 * 5 or x / y + w * z
The selected tree is built when ReformTree is pressed, by adding each element in turn. If JustShow is ticked the completed tree is shown; otherwise if Animate is ticked, the tree is built slowly (you can alter the speed) or you can press ShowNext. In either case the search/insert/reorganise operations undertaken are shown.