demonstrates Tkinter widgets Frame, Button, Label, Entry, Text and Scrollbar by converting Joe's calculator example to tkinter. Button widget explanation starts at line 123, Label at lines 160-168, and Entry widget at lines 170-176. You saw the Text widget in the ‘Tick’ example, but here we have two of them, one with a new widget, the Scrollbar.  The Text – Scrollbar linkage runs from lines 184-204. Notice that the original Python code transfers almost directly from the functions, with some minor changes, but the defining and placing of the control widgets requires new code.  It every case this 'new code' is longer and more involved than the equivalent simplegui code, which to me shows what a nice job Scott did in simplifying things for teaching. 

The next three programs will modify this calculator, so it’s worthwhile going through this example carefully.