How to grant some (!) devices access to network but all others have to provide passwords

Hi, all! I'm pretty sure this is a very basic question which might have been discussed in the past already. But I'm new in this area so you might apologize this silly question.... In a school all devices (students laptops, mobiles, tablets) have to use username/password via Freeradius to get access to WLAN. But there are some well-defined school-owned devices (laptops, tablets)  which should connect to WLAN  immediately w/o any credentials. Which options do I have to realize that? MAC checks? Certificates? Thanks for your help Uwe