Locking Your Computer
It's a good practice to lock your computer screen when it is going to be out of eyesight, and/or when you are walking away from it for more than a few minutes. To do this, simply press the system key (typically the little key with the Windows logo on it [also shown below]) together with the 'L' key.
Pressing those two buttons together will lock your screen, leaving everything you had open still open; it will just require you to enter your password to get back to it. Again, this is a good habit to get into to protect, for example, sensitive student information in your Gradebook. It also keeps students from messing with your desktop background and such things.