Do not comply. Download, fill in and modify as needed the letter provided by Frontline Doctors here: https://americasfrontlinedoctors.org/legal/masks-the-law/ - then go to the school, hand it to the Principal and let them know - "if you put a mask on my child, I'm suing you - both personally and professionally, and any other ISD employee that assists you".
Do not comply. Download, fill in and modify as needed the letter provided by Frontline Doctors here: https://americasfrontlinedoctors.org/legal/masks-the-law/ - then go to the school, hand it to the Principal and let them know - "if you put a mask on my child, I'm suing you - both personally and professionally, and any other ISD employee that assists you".