It may help to think of it this way: Rubare (to rob, steal) is a transitive verb i.e. one that can take a direct object pronoun (taking a direct object pronoun answers the question "who is robbed?" = them, us, he/she/it ) Rubano means "they rob" so the question is "who do they rob?" The answer is "us" = "ci" See this for more about direct object pronouns: http://italian.about.com/library/fare/blfare116a.htm Hope this helps!
I posted on the Wordreference forum:<pre>
Can you tell me which of the following mean "They steal his work": Loro lo rubano il lavoro Loro gli rubano il lavoro Loro rubano il suo lavoro</pre>
and a native speaker responded:<pre>
The first isn't correct... the second is the right answer! Though the third is correct, seems not natural to me..</pre>
The Duolingo example just leaves open whether the pronoun is indirect (as I thought) or direct (as you thought).
I also looked up rubare (http://www.wordreference.com/iten/rubare)
and found this example:
Marco è riuscito a rubarmi un solo bacio This says "Marco has succceded in stealing from me a single kiss" (or maybe "one
chocolate", stupid example).
I also found
Quello che viene a rubarci il lavoro which means "What comes to steal our work" (http://www.celesteprize.com/artwork/ido:192537/)
This may clear things up a little. Rubare takes both a direct and indirect object, though you don't always have to specify both.
In this Duo example 'ci' is an indirect object, indicating 'whom' as they most often do. So in this case we are being robbed.
In Peter's example 'gli' is the indirect object. So in that case he is being robbed.
In both examples, the direct object is 'il lavoro', answering 'what' is being stolen. If referring to it with a direct object pronoun we would use 'lo', getting the sentences: "Loro ce lo rubano" and "Loro glielo rubano"
I think some confusion arose because 'ci' can be both a direct or an indirect object pronoun. Sometimes when trying to work out these verbs it's more helpful to think of the indirect object as signifying "who is the third party" rather than "to who". "To who" in english makes us automatically think of "towards", while when we say rob we think of moving the item "from".
Overall, I wish Duo would expand the sections on direct/indirect objects and reflexives introducing them over separate lessons and demonstrating how many verbs in italian use them in ways quite different to their english equivalents.