What words in other languages are cognates of "kudri"? It's always interesting figuring out from which languages Zamenhof was borrowing.
why is it kion and not kio? what is the difference because we learned kio estas tio = what is that.....so why isnt this kio vi kudras?
Because "kudri" is a transitive verb, so you need to identify the direct object. If you use -n in the answer, you also need to use it in the question.
Ex: Kion vi kudras? Mi kudras pantalonon
If the n in kion is used to make it the direct object, what would kio vi kudras mean? Better yet, is there any case where kion/kio isn't the direct object? For example, in kio estas tio, kio is the direct object right? So then why doesn't it have the n?
In that case the verb is "esti" which the accusative isn't used, because there is no object really. X estas Y is like saying X = Y.
As an english speaker this whole kio versus kion thing is going to mess me up but good.
Just use kion whenever there action involved and kio whenever you just want to know what something is.
Kion vi kudras? You are sewing a thing.
Kio estas tio? A thing is existing.
Practice makes perfect.