In a previous blog article, I wrote about the challenge learners of the German language can face when declining adjectives. There are four cases in German, 3 genders and one plural. There are three ways of declining an adjective: with an indefinite article, with a definite article and without an article (zero declension). That comes to forty-eight ways of declining an adjective! Getting the adjective endings right when speaking German is a sign that the speaker can master the German language. Not many foreign speakers of German get it right; even native speakers make mistakes. During my German lessons here in London, I use the following conceptual schema, which, with a lot of practice, lets you remember the endings very quickly:

I’m revising for an A2 exam. The flowchart here is incredibly helpful.
Great to hear that it is of help. Where are you taking the A2 exam? Good luck with it!
What does it mean for the article to be its original form?
In its original form means no change from the Nominative -> neuter, feminine and plural do not change the Accusative (only the masculine changes) and then they all change in the Dative and Genitive.