Adjektivdeklination · the signal relay
A German noun phrase signals its case & gender one time. If the article carries it, the adjective relaxes. If there's no article, the adjective takes over. Pick a table and watch the endings morph.
Weak: A definite article is present and carries the signal, so the adjective relaxes to just -e or -en.
der gute Mann
Article der · adjective ending -e · article carries the signal
Merkhilfe: The definite article already shows the case, so the adjective relaxes to a weak -e / -en. The strong endings mirror the der-words: -er (der), -e (die), -es (das), -em (dem), -er (der/Genitiv).
Make it stick
Twenty-four phrases across all three tables. Read the article (or its absence), then pick the adjective ending.
Der gut… Mann kocht.
The good man is cooking.