It's that seasonal time of year when it's a good idea to back up your laptop. Parting with your laptop for a few hours at school to leave it plugged in to back up is only one option- you can always back up at home too by getting an external hard drive. Here are some tips for backing up your data on your own:
Time Machine is Apple's backup program that is built into your laptop. Time Machine automatically backs up your entire Mac, including system files, applications, accounts, preferences, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of all your files, but it also remembers how your system looked on any given day- so, if something happened, not only would you get all your files back, but everything would look exactly as it did before. No more setting up all your preferences again!
This article from Apple gives more detailed instructions on how to set up your own Time Machine.
Here is a pretty good YouTube video I found about How to set up Time Machine backups to an external USB drive.
As someone who recently had a huge scare thinking I lost every file on my personal home computer because I didn't take my own advice of backing up as often as possible, I highly suggest you backup as often as you can :)