Below are steps to setup a Google Voice number that allows you to give out to students/parents. You can set this number to forward to your cell phone during certain hours of the day. The great thing about a Google Voice number is your parents/students never have your actual phone number. You can also make all calls from your Chromebook!
You can not use your school provided account for a Google Voice number as Google has removed the free version from schools(unless you had one before the transition). You will need to create a new personal Google Account to create your voice account which is detailed in the attached document. This service is free. If you are prompted to pay, you are opting for premium features that you do not need.