As you read this, look at your computer DOCK at the bottom of your screen (or on the side, if you chose to place it there.) Do you see the little lights under some of the applications? Those lights indicate that the program is open. You may have closed the window, but the program is still open. If you have several applications open, it is draining your resources and, possibly, the school's resources (if the application goes out to the server).
To close the application properly, you will need to click on the icon and either hit Command-Q, or go to the toolbar at the top of your screen, select the programs name and select Quit from the drop-down menu. When the program is closed properly, you will no longer see the light under the icon in the DOCK.
So, the tip of the week is.....try to limit the number of programs that are open at one time. You will find that your system will run faster! An added benefit will be that as more resources are available building-wide, you will notice your students being able to log on to the laptops faster. That's a great goal!