"The red strawberry is good."

Translation: Die rote Erdbeere ist gut.

[zimator]

Why rote? I haven't found anything about using rote instead of rot

[qbufm07]

Try this post: http://duolingo.com/#/comment/48485?from_skill=1f4b62bb1eb46d77d915d61eb9b1c49d

[mikelucas]

Having read the other user comments, and followed the link given, I want to know how as a beginner I am supposed to know what appears to be a complex grammatical issue, and one well beyond this level? Expecting a novice to understand why 'rot' and not 'rote' is basically unhelpful and unfair. I will write the answer down, so I can complete the level, but it will be completion without proper understanding and surely this is the very thing Duolingo should strive to avoid.

[Sonom5]

I completely agree. Duolingo needs a system to teach grammar and sentence structure

[nikosei]

Are all colors declinable? Like how many forms does “rot” have? Rote, roten, rotes?

[pada.online]

Yes, the suffix of adjectives depends on the case:

• die rote Erdbeere - 1. Fall (Nominativ) - Was?
• der roten Erdbeere - 2. Fall (Genitiv) - Wessen?
• der roten Erdbeere - 3. Fall (Dativ) - Wem?
• die rote Erdbeere - 4. Fall (Akkusativ) - Wen?

The suffix of adjectives also depends on gender of the noun:

• ein roter Eimer - male (der)
• eine rote Erdbeere - female (die)
• ein rotes Kleid - neuter (das)