My wife is a teacher and this is pretty much the same policy at her school. When they are doing some cool experiments or dissections (she's a science teacher) the kids will ask if it's okay to take their phones out to take pictures, but then they pit it right back. She has told me that she does have to give kids warnings from time to time that they shouldn't have their phones out, but most other teachers confiscate on sight.
For my son we actually have a medical plan on file with the school that his phone needs to be with him, within Bluetooth distance, at all times to counter policies like this. He is diabetic and has an insulin pump along with a CGM ( Continuous Glucose Monitor) that both communicate with his phone. When his blood sugar goes to high or too low his CGH sends the data to his phone which sends it to his pump, my wife's phone and my phone. We have had this same basic plan in place for years because the schools have had a similar policy for a while.