To be clear, I have had children have a tantrum at my home when they have started at an older age and are learning the ropes at my house. I say this would "never happen with a child I had in my care for so long" because it wouldn't. They may get upset and need to have a big cry, but never a full out flailing tantrum. Maybe I have been lucky. I have clear expectations around behaviour. The children know that their feelings are okay, they learn the best way to express their emotions, they learn to come to me for help with their feelings, etc... They also know what behaviours are acceptable and unacceptable. I would be shocked if any of my daycare kids had a falling down, flailing tantrum, because it just doesn't happen here. I'm not trying to sound like I'm judging anybody, it's just the truth.
What leads up to these tantrums? Is it a new thing or if you look back has she slowly been moving towards this behaviour happening?
Our day is just so predictable there would be nothing to really set a child off like that.