"The boys need a shirt."
Translation:Chłopcy potrzebują koszuli.
I wrote "Chłopcy potrzebują koszulę" and it was wrong. Being a native speaker is not enough to master polish I guess :D
Think it should be "shirts" for clarity, you wouldn't use the singular if you wanted them all to get shirts.
This is fine and realistic. Example: They might be tie dying a single shirt as a group
They aren't all necessarily going to wear it. They could be using it for something else.
Is "koszula" here genitive because "potrzebować" takes its object in the genitive?
Would "Chłopcy potrzebują koszulki" work? I used the wrong case but it only suggested "koszuli"
Technically "koszulka" = t-shirt, but I guess a t-shirt can be also just called a shirt, so added.
It's Nominative plural, but also Genitive singular. That's common with feminine words.
In speech, there usually isn't. Most people pronounce "ę" (if it's the final sound of a word) just as "e" or nasalize it just a bit.
That's a very good question. I have no idea. It's completely illogical, but that's just how it is: "chłopaki" for some reason are 'not masculine-personal plural' in Nominative. But in other cases they behave logically, like 'masculine-personal plural'.