DAS SIND !!!!
ok so from my studies on Duo. (( Das sind )) means they are // these are // those are//. Now my question is how can one tell the difference ?
E.G. Do you prefer these things or those? translates to: Möchtest du lieber diese Sachen oder jene?
Although jener/jene/jenes exists, it already has an old fashioned touch. It is often replaced by: Möchtest du diese Sachen hier oder diese. Möchtest du die Sachen (hier) oder die (dort).
You will know the difference by context.
For the most part I've gotten them right just by the feeling I get with the context but it is still hard.
It is hard, because in Duolingo there isn't any context in most of the sentences :) I believe it is easier in "real" conversation or longer texts.
It is all about context. If you are talking about people, then it will be "they are". It is worse than that as "Das sind..." is often used in expresssions which when translated end up to be singular in the English expression "It is.." or "That is..." Now, this would be a general use for "Those are..." which could often be "These are..." as easily. When you really mean "These are..." specifically meaning location, you would use "Dieser", though again when you are using "These" or "Those" as an expression you can again say "Diese Hunde!" because it is less important where the dogs are as much as it is important that you are talking about some very specific dogs. If you want to specifically say "they", you would use "sie" and again there are expressions which use other words.