My son (nearly 6) keeps losing his coat outside at lunchtimes. Today it was raining all day so coat got carried home wet while he got rained on. Lunchbox keeps getting left in the hall. He's in year one and we did not have this problem in reception. He's also come home in another child's trousers instead of his own, I sorted this with other mum and we laughed about it.
I do think this is partly down to his personality and I tell him everyday remember your lunchbox etc.. but he's not the only one. Another parent has had an expensive logo jumper lost already.
YABU- son should be more responsible for his things.
YANBU- school should help more.