I would say no. Teaching students how to use the card catalog, whether physical or electronic, is useful. But the Dewey and Library of Congress Systems are nothing more than ways to number the shelves, really. Having students memorize the system is rather pointless; I don't need to know how Google organizes its information internally to get what I want online, after all. The crux of the matter is: Can you find what you are looking for? As long as a student can use the catalog and read the tags on the shelves, then they are set on the cataloging issue.
Of much greater import is the point that #7 makes; what most students really need to learn is how to search effectively. This includes understanding how to make a list of key words or tags, and a grasp of the different types and qualities of references that are available to them. All you have to do is look at how poor a job most students do at putting tags on their enotes questions to realize that knowing the Dewey decimal system isn't going to help them find information - organizing their thoughts so they know what they are trying to find has to come first.
Yes. While it is not particularly applicable to the newest technologies, it is still used in libraries for physical searches. More importantly to me, students always benefit from understanding how things are structured and organized. Learning how things are categorized and sub-categorized is important in outlining and other areas which are not deemed outdated.
I never learned it, but I used the Ursus library system here in Maine to track down books in the library. I think as long as we have libraries, it is an important part of cataloging, but it might become obsolete very soon. However, it's still important for older books which might not be cataloged online.
Our school's library just recently abandoned the system and instead organized all of the books similar to Barnes and Nobles or other popular bookstores. Students couldn't find books any other way, but they know to look in the mystery section or the Sports section of the nonfiction section. Students visit bookstores more often than the visit libraries and more and more students are visiting bookstores on iPads, Kindles, or their phones without leaving their room. It’s how they find books, and soon it will be the only way they know to pick out books.
I don't know what audience of students needs to actually learn the Dewey Decimal system -- they only need to be taught how to search for titles of books that might be useful to them and then how to find them on the shelves -- no matter how they are organized. I would argue that creating good searches using technology is more important. Students need to learn how to broaden or focus a search in order to find a variety of possible sources. I do like the idea of the library being organized by topic/subject though -- lots of times when I "look up" one book and go to the shelf to get it, I "accidentally" find even better books related to my topic that I didn't find in my initial search of the catalog.
I suppose there are still some libraries out there that are not yet automated, but as it is merely a vehicle to categorize, organize and locate books, pretty much any system, automated or otherwise, that accomplishes the same thing makes teaching the old system unnecessary. I think the days of the card catalog are long gone, and if the Dewey Decimal system needs to go in the dustbin of history, no big deal. As long as people keep finding and reading books (or eBooks).
If it is taught, I wouldn't spend a huge amount of time on it. It's helpful to know in general how both the Dewey and LC systems work (the latter seems by far the more logical of the two), but I don't think detailed knowledge of them is necessary to most people. I basically make my living by reading books (and teaching about them) and all I need in order to do so is know how to read call numbers and find books on shelves. My wife, who catalogues books for a public library, does indeed need to know the Dewey system in detail.
I don't really think that it was relevant to teach the Dewey Decimal System or the Library of Congress System back when I was in school (HS class of '86) and it is not important to teach it now. And this is from someone who worked 6 years in libraries.
There's no reason that kids should have to learn what number range corresponds to what subject or anything like that. They aren't going to need it in grade school and then, when they get to where they do need it (probably the LC System since hardly anyone still uses Dewey in college) they'll be able to figure it out themselves.
There are lots of other things that should be taught. Spending time learning Dewey makes little or no sense.
I do not think it is necessary any more. There are three reasons for this. First, there are just too many books out there now and there is no sign of it slowing down. So, we need a more efficient system. Second, even if books are not digitized, library have everything now on-line, at least university libraries. In time, all libraries will be like this. Third, with a digital age, things will change even more. Efficiency and ease of getting information is more important than keep an outdated system. The Dewy Decimal System worked in the past. Now it is time to move forwards.
I taught 3rd grade last year and I gave every student bookmarks, which I handed out to students when we went to the library. They used these bookmarks to mark the spot they had taken a book from so they could put it back in the correct spot if they didn't want it. On the bookmark I had the categories of the dewey decimal system so they could use it to find books if they needed to. I highlighted the ones they would most likely use (fiction, biography, drawing books, etc.) and ones covering subjects we would cover during the year (geography, US history, geology, etc.) so they didn't get too overwhelmed by the many classifications, but they had them if they wanted to look up something specific - many of them used other classifications according to their interests. I also sent a bookmark home with them with a note to the parents about how it works and encouraged them to use them at the public library.
I did not teach the system outright, but they become familiar with it and eventually know what numbers their favorite subjects are in - I heard students say things like "Oh, the biographies are in the 920s" which was kind of cool. It's important they know how to use the system, but I don't believe in memorization for the sake of memorization.