My child has never, ever said he was a half age. When people would come up to him and ask if he was 6 and a half he would look at them as though they were crazy and should shut up. Then he would inform them he was 6, he does not turn 7 until his birthday. If it was near his birthday and some unfortunate soul, like say his mother, would say "You are almost 8" he would lose his ever loving mind and explain emphatically that he was 7 he does not turn 8 until Tuesday, even if Tuesday was the next day.
My child has opinions on age and responsibility. Preparing food to eat was not his responsibility, it did not matter if it was a sandwich, a bean and cheese burrito, or a 5 course meal, it was Mom's responsibility and in the last 6 months he has come to recognize that Dad can also make food worth eating, but was still not his responsibility to prepare his own food. It did not matter how much his mother told him he could make it, that he had made it before. No, he was being abandon to adult life much too soon in his way of thinking.
My child yesterday, he not only prepared his breakfast, granted a reheated leftover burger, he also prepared his own lunch, a turkey cheese and mayo sandwich with a glass of milk he poured himself, and let me know that he was wearing his last pair of clean underwear, and shirt would I do the laundry please. Then helped fold and put away all the clean clothes.
It was as though a young man sprouted before my eyes. At the end of the evening he was, justifiably, proud of what he had done and how he had carried himself through the day (we are ignoring the testing portion of the day) and said, "Well I'm 9 and a half now. Right?" we agreed "I need to be more responsible, I will be 10 this year"
So I guess nearly 10 is his thresh hold for responsibility. Please let puberty wait a couple more years. I'm enjoying this stage so much.