Die Apotheke (f) but you say "In DER Apotheke"? Someone explain?
Just as I'm starting to qualify most of my masculine or feminine nouns correctly, I come across this (another) bump in the German language road. If Apotheke is feminine, why do you say in der Apotheke?
You use 'der' because of the preposition 'in' which can be followed by either the accusative or dative case. In this instance, it takes the dative case. For female nouns, this means the 'die' becomes 'der.'
The word 'in' puts it in dative case
Nominative case = Die Apotheke
Accusative case = Die Apotheke
Dative case = Der Apotheke
Genitive case = Der Apotheke
Here to better explain:
I see you have learned a bit of French and Spanish, where the noun gender signifiers are consistent: in French, "le chat" is always "le", no matter what context you're using it in. Unfortunately, in German, these signifiers are not so simple. Think of it as the difference between "he" and "him": you would say "He is talking", but you wouldn't say "I talk to he". In that grammatical case, "he" becomes "him". Similarly, the German word Apotheke, when it stands on its own, is "die Apotheke", but if you're saying that you are IN the Apotheke, then "die" changes to "der". As others have pointed out, this is an example of the dative case. German has 4 cases, and these usually change the articles. It seems very strange at first to a native English speaker (or even a native speaker of French or Spanish, where, again, the noun articles don't change depending on case), but you get used to it after a while. The cases are one of the most challenging parts of German for people studying it, so don't be discouraged by them; you'll get the hang of it after a bit of practice.
Because you're learning your language with a system that's embarrassed about grammar, so you have to guess in a frustrated fashion. Go get yourself a proper German course and use DL for a bit of fun. It is fun; but it's not a way to learn a language.