An adjective before a noun (der schöne Tag) needs an ending that agrees with the noun's gender, case, and which article type comes before it. This is genuinely A2-level complexity - go slowly, and lean on the "predicate adjective" escape hatch below whenever precision isn't required.
When an adjective comes after a form of sein rather than directly before a noun, it never changes - this is the easiest, safest way to use adjectives at A1/A2:
Der Tag ist schön. (no ending - adjective after sein)
Die Wohnung ist groß.
If unsure of an ending, restructure the sentence to put the adjective after sein instead of in front of the noun - it's always correct there.
| Gender | Nominative | Accusative |
|---|---|---|
| masculine | der schöne Tag | den schönen Tag |
| feminine | die schöne Wohnung | die schöne Wohnung |
| neuter | das schöne Haus | das schöne Haus |
After a definite article, the ending is almost always -e, except masculine accusative, which gets -en - mirroring the der→den change from Lesson 7.
| Gender | Nominative | Accusative |
|---|---|---|
| masculine | ein schöner Tag | einen schönen Tag |
| feminine | eine schöne Wohnung | eine schöne Wohnung |
| neuter | ein schönes Haus | ein schönes Haus |
Here the adjective ending has to do extra work to signal gender, since ein itself doesn't distinguish masculine/neuter in the nominative - notice the ending carries the -er/-es that the article doesn't show.
| groß | big | klein | small |
| schön | beautiful | neu | new |
| teuer | expensive | billig | cheap |
Cross-checked against the Goethe-Institut A1 practice materials.