How do children learn? Scientists do not really know.
This sentence is quoted from a certain English-learning book published in Japan.
Does the sentence, "Scientists do not really know.", mean that scientists don't know "almost nothing" about how children learn? If the sentence doesn't have a meaning like that, What is the correct meaning?
I think it might mean that scientist don't know everything about the subject, rather than that they don't know anything about it. But it sounds like the beginning of a discussion of the subject, rather than an isolated statement, so reading what follows would probably explain what was meant.
It means that the scientists, do not know a lot about the subject. That can still mean that they know a little bit about the subject.
