It is said that in American schools there are not such lessons as maths,biology,chemistry and instead of it is just one lesson which is called "science".Is it true or not?
Sure thing! I wouldn't say it's not systematic. It's more like, in elementary school, you get a general overview of those complex subjects so that you can have a solid foundation for learning all math and science principles. Then, in middle school and high school, you take individual courses to study each of those specific topics in-depth.
So, in a sense, children do learn those concepts but not in a systematic way until later.
Yes, that's true. It's just that we do all of that in classes that are more simply called "math" and "science" in elementary school. For example, a 3rd grade student may learn multiplication, division and simple algebra principles in "math" class, and then go to "science" class and learn about geology, astronomy, simple chemistry (like how to build a volcano at home), anatomy, etc. But we don't break our math and science classes down into excusive specialties like a full term of only "geometry" or a full term of only "calculus" until later.
I thought children in USA elementary schools were taught addition, subtraction, multiplication tables etc, as well as spelling and some basic physic laws like gravity. Is it not accurate?