Breakdown of Ein schmutziger Ofen ist ein großes Problem.
sein
to be
ein
a, an (eine)
groß
big / tall
das Problem
the problem
Questions & Answers about Ein schmutziger Ofen ist ein großes Problem.
Why does schmutzig get the ending -er here?
Ofen is a masculine noun, and here it is the subject of the sentence (nominative case). When you use an indefinite article like ein that doesn't have its own ending, the adjective has to step in and show the masculine gender. It does this by taking the -er ending, which reminds us of the definite article der.
Why does groß end in -es in ein großes Problem?
This follows the exact same rule as above, but for a neuter noun! Problem is neuter. Since the word ein doesn't tell us the gender, the adjective groß takes the -es ending to show us that the noun would normally take the neuter article das.
Why is ein großes Problem in the nominative case instead of the accusative?
Because of the verb ist (from sein, meaning to be). This verb acts like an equals sign instead of describing an action done to an object. It connects the subject to a description of what it is, so both sides of the equation stay in the nominative case.
Are Ofen and Herd the same thing?