Don’t understand the lesson

Question

I’m sorry this is the worst lesson I’ve found on this site. I’ve read it several times and still don’t know which to use in conversations or writing

Silvia Piriz · Accepted Answer

Hola Jeremy W. and Devin P.
What Devin explains is actually the core of the issue and it’s not really about conversation versus writing. The distinction between ser and estar is grammatical and semantic rather than stylistic.
Ser cannot be followed by adverbs like bien or mal; it must be followed by adjectives such as bueno or malo.
Estar, on the other hand, can be followed by adverbs (estar bien / estar mal) or by adjectives that describe a temporary state.
The comparison with English is helpful here. In everyday English, people often say “I’m good” when they really mean “I’m well”, even though those are technically different. Spanish does not allow that kind of flexibility. You can’t say soy bien the way English speakers say “I’m good”, because Spanish keeps the adjective/adverb distinction much stricter. That’s why this lesson isn’t about what sounds natural in conversation, but about which structures are grammatically possible at all.
So when certain answers are marked wrong, it’s not because they would be unusual or unnatural in real-life speech, but because they combine elements that Spanish simply doesn’t allow. Once you look at it through that lens — ser + adjective versus estar + adverb/adjective — the rule is consistent and applies equally to spoken and written Spanish.
That said, we really appreciate your feedback. We’ll definitely take it into account and review this lesson more thoroughly in the future to see how we can make the explanation clearer and more intuitive for learners.
Cordialmente
Silvia

Devin Prowell · Answer

I believe it’s similar to English. Ser can’t be followed by an adverb such as bien or mal, it has to be followed by the adjectives malo or bueno. In English, if someone asked you, “How are you?” You would answer I am well. Saying, I am good, would often be considered wrong. Saying I am good might indicate that I am a good person rather than the temporary state of being well. Spanish makes this differentiation more clear than English by using two verbs for “to be” Ser is used to describe permanent qualities such as being a good person, “I am good” good an adjective translates to bueno while estar is used to describe a temporary state of being, “I am well.” Well translating to bien. Estar can also be followed by an adjective but the adjective’s meaning will connote a temporary state such being in good health rather than a permanent quality such as being a good person. To make it clear that you are speaking of a permanent quality you would have to use the adjective with ser.