Occasionally I see a reference to categorized noun declensions (e.g., first, second, third). I would imagine some question whether or not learning about such declensions is essential to learning the Russian language, but it does appear that this categorization of declensions is being taught in this way to some students and I'd like to be able to more fully understand the questions or comments written about such declensions. However, I haven't had much luck in finding anything truly helpful. I find references to such resources few and far between and not all that comprehensive. I have visited the following thread:
Order of declensions (склонения)
and it was very good. I even visited some of the links listed in it, but it appears that the only references I can find with noun declension categories that categorize nouns, for the most part, are for those in singular form. Are there any for those found in plural form only (like the word "люди")? And in the absence of any pre-established categorization of the declensions of nouns found in plural form only, has anyone reading this discovered or noticed any particular patterns (e.g., plural nouns ending in __, are usually __ in the genitive plural)? Or is there just not enough of them to bother creating rules and categories for? In a quick glance of the Top 500 Russian Nouns, as listed at MasterRussian.com, I think I only saw a couple of nouns that appear to be in plural form only (i.e., деньги, сутки). Based off of this, I presume that the number of Russian nouns found in plural form only is less than 1 percent and quite likely very difficult to make generalizations about or categorize. But if any do exist, especially if they are online and free, please share them with us. (Ideally, there's some sort of online dictionary or database that allows me to type in a word and returns with information that includes what declension category the word belongs to.)
Also, while I am at it, does anyone know the history of teaching the Russian language with respect to the teaching of noun declensions by category? Is this something that was popular at one time but has fallen into disuse for some reason? Is this method of teaching Russian still in use and/or more popular in countries that use a case system (e.g., Germany)?
For the record, I decided to post this question here after reading a comment someone had made in a discussion thread in Duolingo's Russian for English Speakers course. One of the users asked:
Is "люди" a third declension noun when "человек" is first declension? How can one tell that its genitive plural should be "людей" and not "люд" or "людов"?
You can link to the thread below:
Is "люди" a third declension noun ...?
Thanks in advance for any resources you can share or insight you can provide.