"I do not like him."
Translation:Ich mag ihn nicht.
I have found this to be true in many foreign language courses for English speakers. It was true of my high school Latin and I've heard friends taking French complain as well. In American public school we learn a word can be a noun, a noun can be a subject or a direct object—that's it. That is as much as I was ever taught about it. If anyone knows of a good place to learn about "cases" and the corresponding English usage, I'd appreciate a link. If I could master the concept in my mother tongue, learning German would be much, much easier.
Qemily1 - German is a technically difficult language to learn. Unfortunately, there is a certain amount of grunt memorization that goes into learning the pronouns and the cases they go with. Generally: Nominative is the subject of a sentence; Genitive is a possessive; Dative is an indirect object and Accusative is the direct object. It's taken me 40 years of study and four years living in country to get a grip on all this. Don't beat yourself up if you don't get it all in the first month or two. Get a good used german grammar book on Amazon.
Thank you jshous. My complaint was more that regular schooling did not even provide the basics to figure it out. Diagramming sentences was offered only in 8th grade and my teacher chose to skip that chapter, calling it irrelevant. So I have had to go back and search out, "What is an indirect object?" To further complicate things, when direct objects were taught, it was called the Objective case, not the Accusative, so it took more time to figure out that they were not two separate things. I did not even have the skills to read a chart that showed the different forms of a word! Since I discovered that I am not alone in this, it would be nice if duolingo offered a "remedial short course" on cases.
I have little to add that has not already been said. "Ich mag ihn nicht" is correct. One can also say "Er gefällt mir nicht" which is also correct. Ihn is used because it's a direct object hence accusative case; where ihm would be indirect and dative case. It's one of those things that makes german a crazy language for an english speaker to learn.