I fully understand that you want to defend and protect your daughter, but as I see it:
- Your daughter was provoced and attacked the other child, which you claim she was "developmentally unable to prevent"
- The other child did not purposefully provoke your daughter, it was "developmentally unable to prevent" the situation just as much as your daughter
I think it's better for her to learn to cope in difficult situations. I don't mean overcome her autism and act like a "normal" child but find her own coping mechanisms in a world that will put her in challanging situations over and over again.
You cannot expect her teachers to hover like a guardian angel and deflect any negative inputs from the world. They have to take care of all children equally.
But you can give them and your daughter a kind of "magic tool" that lets your daughter express without struggle that she is in a difficult situation and requires help / intervention. That can be a short sentence, a physical object or a melody.
You explained that her usual coping mechanism didn't work.
My daughter generally regulates herself by leaving uncomfortable situations. Here they were on a field trip and she was trapped in a confined area.
Imagine the same situation, but now your daughter stands up, goes to a teacher and presents her "magic tool". There would have been no chance of overlooking or misunderstanding the situation now. If the kid followed her, the teacher would probably hold it back to talk to your daughter calmly first.
Some examples of what this "magic tool" can be:
- short phrases like "beetlejuice" or "This is bad" repeated over and over. Make sure teachers know exactly which phrase is the "magical" one.
- Any line from a song or lullaby or book that she remembers very well and can recite in stressfull situations
- A colorfull ribbon, cloth, scarf or handkerchief that she always has in her pocket (or wears as bracelet) and can wave around in stressfull situations
- "I'm on the highway to hell" or a similar catchy song or melody that can be sung or screamed
- Any objects that make a distinguished sound when activated, like a clicker toy or electrical doorbell. I strongly advice against bells and chimes and similar objects that produce sounds when not intended.
As to your letter of protest, don't protest. At least not in the way you did in your question.
You can explain the situation from your perspective, but don't blame the other child and don't absolve your daughter of any blame. That's your biased view as parent. Instead acknowledge that the incident was preventable and that both parties did not act maliciously but are not without blame either.
By the way, this would be the perfect time to explain your daughters new "magic tool" to teachers and parents.
Edit in response to comments
I have no experience in teaching children, but in dealing with people on the autism spectrum in several ranges of age.
The "magic tool" is indeed a child-friendly adaptation of a concept called "Safeword". I chose the obscure name because Safewords are primarily associated with the BDSM scene, which could deter people from further research.
In short, a Safeword is a visual or auditory clue that signals a concept or a state of mind that cannot be explained in simple words. Some real-life examples:
- SOS is a Safeword for "I'm in danger, I need help". Most people even understand the auditory code of 3 short, 3 long and 3 short beeps despite having no idea what Morse Code is.
- A panic button is the physical incarnation of a Safeword
- "Incomming!" signals opponents or enemies approaching in a competitive or war setting.
- A siren of a police car or ambulance can be understood as a Safeword meaning "Dire situation, make way!"
- In the BBC show "Sherlock" John Watson uses the Safeword "a bit not good" to signal Sherlock that his behaviour is socially not acceptable.
- Some families or close friends unconciously develop a Safeword on their own like holing hands in a certain way signaling "I need your support" or referring to a past embarassing situation to say "don't embarass yourself again".
The english Wikipedia article is not very elaborate, so I will summarize the concept in my own words.
- All parties have to agree beforehand what a Safeword is and what it means
- All parties have to honor the Safeword. It can be used by all parties.
- All parties must be able to remember and use the Safeword. "Deoxyribonucleic acid" is a bad Safeword because the chances of remembering and actually vocalizing it in a stressfull situation are slim. Whistling is a bad safeword if you have problems producing a whistle in a stressfull situation.
- The Safeword should not be used for situations where it is not needed. Therefore the Safeword must not be a common phrase that could come up in everyday conversations. It must not be a sound that is produced regularily (like clapping your hands) or unintentionally (like a bell chiming at the slightest movement).