How can I disable spell check system wide and internet access temporarily

I'm getting a mac for high school because I have a disability that doesn't allow me to write properly but my school principal said that I have to disable spell check and internet access. Since it's going to be my personal computer also is there any way I can disable spell check and internet access temporarily?

Spell check isn't part of the OS, so you have to turn it off in each individual program that you use. As for disabling the internet, you have a couple options. You can just click on the airport icon in the upper right and turn the airport off. That way you won't have internet access unless you plug in the Ethernet. If you need something more definitive, you can go into network preferences and remove airport and Ethernet from the list on the left. That way your computer won't be able to connect at all until you add them back (which is very easy don't worry).