Additionally if the hair has been on your head for awhile it can give an approximate history of when drug use occurred.
I have no idea what the school is trying to prove but this is approaching police state tactics. It has no bearing on the current time frame or any indication what has happened during school time. Once this information is stored it will be available indefinitely to whoever can access the information. I’d pull my kids out or shave their heads and my some wigs.
Do you understand that it is the parents who want and support this drug testing at that school ?
Parents know that teens can be influenced by other teens, so they want to know if any of the students are abusing illegal drugs, and if their children are involved. Help is provided to the students who fail the test, and the school admin uses no punishment nor records the failure.
This is a win situation for everyone involved and keeps the government out of it, so how is it a 'police state' ?