"Those children do not listen to their parents."
Translation:Copiii ăia nu ascultă de părinți.
Strictly speaking, 'Copiii aceia nu ascultă de părinți.' should not be right. After all, it says 'Those children do not listen to THEIR parents.' Usually, Duolingo makes such distinctions.
The thing is, "Those children do not listen to their parents" is the only obvious way to say this English, while in Romanian the most common way to say it is "Copiii ăia nu ascultă de părinți" (literally, "Those kids do not listen to the parents"; note that the definite article here is dropped after the preposition de, but it is implied). Though "părinții lor" can be used for emphasis, it is not the default usage in Romanian.
No. You can write: acei copii, copiii aceia, or copiii ăia, they mean the same thing. The word order in these is fixed.