Difference between wkładać and kłaść
Duolingo translates both wkładać and kłaść as 'to put'. What is the difference between these words? They are conjugated like this: wkładam, wkładasz, wkładamy, wkładacie, wkładają and kladę, kładziesz, kładzie, kładziemy, kładziecie, kładą.
It's actually very easy.
Wkładać is "to put into" - wkładam ubrania do szafy (I'm putting the clothes into the closet), wkładam masło do lodówki (I'm putting butter into the fridge), and so on.
Also, it can mean "to put on" with clothes and shoes: wkładam buty, wkładam koszulę.
Kłaść is "to put on" - kładę ubrania na stole (I'm putting the clothes on the table), kładę książkę na półce (I'm putting the book on the shelf), etc.
Wkładać - I would think to remember it by the 'w' at the beginning, which makes sense (literally, more or less); especially in both the examples Jellei gave: putting things into a recepticle (lodówka, etc.), and putting limbs and digits into articles of clothing (buty, rękawiczki)
Very interesting question, I didn't even think about it. Yes, yes you can! Na półkę/na półce is correct, and so is na stół/na stole, and so on, with wherever you want to put something on.
The difference being: your version, being in Accusative, shows the direction (where to, куда); while my version, with Locative, shows the place where it's going to be put: (simple 'where', где).
I also wanted to mention the perfective forms, now that I'm already writing something. Perfective from "wkładać" is "włożyć", perfective from "kłaść" is "położyć".
Wonderful, thanks for the reply. It seems to me there is some kind of divide for this question, look at this topic for example: http://forum.wordreference.com/threads/k%C5%82a%C5%9B%C4%87-na-p%C3%B3%C5%82ce-na-p%C3%B3%C5%82k%C4%99.1378154/
The reason I'm asking is because for instance in Russian it would not be correct: one has to say "кладу на полкУ", and not "на полке" (which as you've pointed out is the locative).
Such similar languages, but still so many differences... anyway, this morning when I read your previous comment I found this - the question is actually about something completely different, but professor Bańko says also "Owszem, można powiedzieć „Połóż książkę na stół” (eksponując kierunek), a nie tylko „Połóż książkę na stole” (co eksponuje miejsce)." - therefore, in Polish we can either 'expose' the direction, or the place.
You can use both forms and you will be understood by a native in both cases. The distinction that "na półkę" focuses on direction and "na półce" focuses on location is purely philosophical and - IMHO - it only tries to formally explain why both forms are correct. In real life however both versions are used interchangeably without any additional meaning implied.