Translation:You have too many books on the bookshelf.
I agree with your sentiment!
Nunca hay demasiados libros en la estantería.
A shelf and a bookshelf are two different things. As a native English speaker, what you said is incorrect.
I'm also a native English speaker. I wrote shelf, even while understanding that un estante is a single shelf and una estantería is a unit containing multiple shelves. To me, it's valid English to shorten bookshelf to shelf. (I also work in a library and we talk about books and their location nonstop.)
I did the same thing. I think "shelf" should be accepted. Check out examples lower down on this page: http://www.spanishdict.com/translate/estanter%C3%ADa
By definition, a shelf is one horizontal board attached to a wall, and "shelves" are a number of boards attached to a wall. Thus, a "bookshelf" is a shelf that a person puts his or her books "on." If say that you put your books "in" a wooden shelf, you are saying that your books are embedded in the wood. (Of course, it goes without saying that shelves can be made of other materials besides wood.) The correct preposition to use when speaking of "bookshelves" is usually "on/on top of/sobre."
Bookshelves and bookcases both can be built in, but only bookcases can be stand-alone pieces of furniture that, by definition, must have tops, sides, and bottoms, with backs being optional. Sometimes, people take freestanding bookcases and mount them on the wall with brackets. Whether a bookcase is freestanding or mounted you put a book "into" a bookcase because bookcases have a top and sides. With the word "bookcase," the correct prepositions to use are "in/into/within/inside/adentro/dentro."
I think this varies by region. Here, a bookshelf can mean a single shelf, but it can also be interchangeable with 'bookcase' or used to refer to a specific shelf within a bookcase. For both of the latter two, 'in' is used, though 'on' is also used for the third one.
Agree. I can't say that I have heard people say they have books 'in' a bookSHELF. I would say, and mostly that I can recall hear people say, 'on' a bookshelf. The same that something is on a shelf not in it. Yes, in theory you could say it, but conversationally I don't hear that.
as a native English speaker I would always say that things, books or whatever, go on to a shelf, not in it.
I don't think "shelf" is a good translation, since "estantería" is something composed of or containing shelves. The concept is singular, whether referring to shelving or a bookcase. However, it is generally not a single shelf. That would be "estante."
When I think of bookshelf I equate that as bookcase, so I think "IN the bookshelf" could be warranted here. I would use "on" in the case of just a shelf by itself.
Please accept "in" the bookshelf. Native Englsih speakers know intuitively when to use "on" (to of bookshelf) and when to use "in" (one of the interior shelves of a bookshelf).
"You have too many books on the shelving" marked incorrect. Stated correct was "shelving unit". Please help me understand where "unit" is implied.
What it shows you are options for translations that may or may not be correct. I believe what it was looking for is bookshelf or bookcase.
"You have too many books in the bookshelf." marked as wrong.
Duolingo, please stop trying to teach me English, and teach em Spanish instead. If I set something on top of a low bookcase, I would use 'on'. However, if I'm talking about the whole item as a container for books, I would say that there are lots of books in the bookcase.