"With the parents"
Translation:Mit den Eltern
Hm, because you need it? :) I'm sorry, I'm not so good with explaining grammar, but I know it is because this is the accusative case.
I can give more examples too:
Ich sehe die Hunde und die Kinder.
Ich spiele mit den Hunden und den Kindern.
If it's still unclear, maybe someone who knows more about the german grammar can help.
In dative form plurals take -n to the end and feminines take -r. I came here to ask why die eltern takes -n, instead of -r but now i see it is count as plural :) Bettter explanations are here : http://www.duolingo.com/comment/72?from_skill=bdcb9d10263c7d82f2b5f95ff788fb47