My twin daughters just started elementary school I am so full of happiness. 
That's so sweet! What ages are they? For elementary school, obviously they're somewhere between 6 and 12, as US elementary schools have 6 grades, with those ages corresponding to them. But they've been 6 to 10, and 6 to 14, as well, in some areas.
They are 5 they will be turning 6 in November they love it so far which is great because elementary years is the most important in schooling it shows them the importance of education. 
That's pretty cool! Ages for elementary school vary by country, so sometimes it can be much different. But in the Western world, elementary school is always just one part of the compulsory education that's taught and required.
Yes it is required where we live as well kids have to start if they are 5 it's the law and I agree the teaching style etc. is different from state to state heck even county to county.
Education in China
Education in China is a state-run system of public education run by the Ministry of Education. All citizens must attend school for at least nine years, known as the nine-year compulsory education, which is funded by the government. Compulsory education includes six years of primary education, starting at age six or seven, and three years of junior secondary education (junior middle school) for ages 12 to 15. Some provinces may have five years of primary school but four years for junior middle school
12, but some elementary schools have four or eight grades, i.e., up to ages 10 or 14 (also known as the intermediate grades). Basic subjects are taught and pupils often remain in one or two classrooms throughout the school day, except for physical education, library, music, art, and computer classes. In 2001, there were about 3.6 million children in each grade in the United States. "Middle schools" and "junior high schools" are schools that span grades 5 or 6 to 8 and