"The child is playing with its cup."
Translation:Das Kind spielt mit seiner Tasse.
Her is "ihrer".
But here's a question though for anyone that can answer. Which would be more correct in German:
- Das Mädchen spielt mit seiner Tasse.
- Das Mädchen spielt mit ihrer Tasse.
The girl is obviously female, but Mädchen is neuter. Similarly, what if (using the Duo sentence here) you saw a girl playing with a cup, and someone specifically asked you "What is the child doing?" Would you answer "Das Kind spielt mit seiner Tasse" even though you can both clearly see it is a girl, or could you use ihrer?
Let's start off simple. "Das Kind spielt mit seiner Tasse." is the most logical and most likely answer. Kids are usually neuter, I've never heard Kind + ihrer. If you want to differ the gender, for example when there are two kids, one of either gender, you would say Junge or Mädchen to make it clear. For Mädchen, you got that right, it's ihrer and seiner, both are fine, I would say 'seiner', personally, since it's in accordance with the article and seems more plausibel to me, therefore.
But: Unfortunately, that's not it and it could be literally anything. Compare this: http://duolingo.com/#/comment/231399
I gave my sister a cup as a birthday present. Now the dog is playing with her cup.
I gave my dog a cup and now it's playing with its cup.
I gave my father a cup, but he was really mad about it. So he left mother and his cup in the forest, cursing the day she gave birth to me.
With context given, all this makes perfect sense and is correct, since possesive pronouns usually refer to something that was mentioned outside duo's short sentences. So, yes, it could be 'her' cup. But it's not the most likely answer.
Okay. I think I get it. Regardless of the "physical" gender of the noun, use the "assigned" gender. You may know given context that "das Kind" is a girl, but if using the words "Das Kind" then use neuter. Similarly, das Mädchen is a neuter noun it is better to treat it as such.
And here we go again already. I just asked my wife, out of mere curiosity, what she would say: Das Mädchen spielt mit ihrer Puppe, since behind the neuter word, there's the actual female child. But it's a neuter word anyway, hence I always use seiner. So it really is just sprachgefühl. (I love that word. It's the perfect apology for not knowing or finding any rules.)
I can't really speak to other languages since I'm a native English speaker, but to other English speakers, using "it" to refer to a person (even a child) is not just grammatically incorrect, it is taken as an insult.
My point is: I would rather not have someone who is learning English to think it's OK (even if it is OK in their language). It could unintentionally cause them trouble.
Seiner means "his" (ihrer means "hers"). Since Tasse is feminine, In nominative case, it would actually be "seine Tasse". But "mit" (along with many other prepositions in German) take the dative case. In such cases, the adjectival ending changes (from seine to seiner).
If you're asking why in English it's "its" instead of "his" or "her"; the site's trying to be politically correct and therefore gender neutral. You should ALWAYS use "his" or "her" if you know the gender of the child.