one of the biggest problems newbees to PLCs have is fear of how to use the hareware with out messing anything up and then debugging correctly.
Using a software emulator doesn't let students work thought this by connecting up a real PLC by RS232 or usb or whatever then powering it up put it in Program mode uploading a file running the program, checking the PLC regristers and counters while online, making changes to ladder logic, uploading changes to PLC without messing up counters for work in process
As far as a teaching document the Allen Bradley published book is great
MicroMentor
Understanding and Applying Micro Programmable Controllers
ˆ 1995 Allen-Bradley Company, Inc. Printed in USA
TM
The micro symbol is a trademark of Allen-Bradley Company, Inc., a Rockwell International company
This has everything up have in your 9 page document step by step with ladder logic and much more.