English adjectives are invariables, which means that
they do not change with the number of the noun, which is described by the adjective.
Adjectives are invariable
a red rose <=>
many red roses
a black telephone <=>
many black telephones
Well, there is a difference in the German version!
German adjectives change with the number of the noun
that is described. Not only this, they also change with
the gender. And now since all good things are three
(a German proverb) they also change in the declension!
The declension of German verbs is unfortunately something
very challenging. In the following we are going to explain
the rules for the declension of the German adjectives.