Tuesday after shcool madness

Tuesday is gym day on our house, so when daughter gets home we have time for a snack, a drink, get changed and out again to drop her off. I then come home make dinner for son and myself, eat and just about have time for cup of tea before shooting off again and pick daughter up.
This week however was more rushed. Pancakes! But with some added temper tantrum and rushing involved.
It started so well with daughter making the mixture while i sorted sauce for Spag bol dinner while she was out. She told me she wanted small pancakes. Fair enough i can manage that, so i set too and started them. That's when it all kicked off. "Mrs M (the headteacher) used oil for the pan not butter" she shouts. I point out that it makes no difference since all I'm doing is greasing the pan slightly to stop them sticking. But NO this was not good enough and a sulk ensued. When i asked for a plate as hers were almost ready the situation go worse- "I only wanted 1 small one, and a big one" NOT what she originally asked for. I pointed this out too, but was promptly told that what she meant. By this time daughter is crying and snapping and i am getting exasperated. I unfortunately snapped back at this point and stated that i didn't know this because when someone tells me they want small pancakes i assume they mean that, not that they want 1 small and 1 big. Daughter starts shouting, so i tell  her if she won't stop then the pancakes will go in the bin and she can have bread and butter.
Son takes this point to arrive home and this makes tings worse as he wants to know what is going on, daughter doesn't want him knowing.
She storms off upstairs bangs some cupboard doors, cries and her pancakes have gone in the bin!
We were having such a nice time together to start with and it ended with her shouting, me shouting and stressed.
To top it off we had to rush to gym to get a new leotard and she was late for her warm up.
Then i had to get home finish dinner and get to a school meeting for son, that finished just in time to collect daughter.
Once home we did have our pancakes in a calm manner and both children went to bed happy.

What an afternoon. I have to wonder what set daughter off like that. It won't be something as superficial as me doing things differently to the headteacher. But if i probe i know i will either get i don't know as the answer or nothing at all.