Learn Hardcore Portuguese (Portugal): Um professor demasiado severo pode transformar um pequeno erro num grande falhanço. - A teacher who is too strict can turn a small mistake into a big failure.

Putting it as um demasiado severo professor would sound wrong, because demasiado severo is describing the way in which he is strict, not classifying a type of professor. Adverbs don’t usually go directly before the noun in Portuguese.

What is the nuance of demasiado severo compared with muito severo or severo demais?

All three express high degree, but with different nuances:

demasiado severo = too strict / overly strict
Implies that the strictness is excessive, beyond what is good or reasonable.
muito severo = very strict
Just a strong degree; it doesn’t necessarily say it’s too much. It could even be seen as positive depending on context.
severo demais = also too strict, similar meaning to demasiado severo
- In European Portuguese, demasiado is more common and neutral.
- demais is also used, but sounds a bit more informal/colloquial.

So in this sentence, demasiado severo is chosen because the teacher’s strictness is being criticized as excessive.

Why is it um professor and not o professor or just professor?

Portuguese uses articles more than English, but the choice of article matters:

um professor demasiado severo…
= a (any) teacher who is too strict…
This is generic: talking about any such teacher, not a specific one.
o professor demasiado severo…
= the teacher who is too strict…
This would refer to a specific teacher already known in the context.
professor demasiado severo… (no article)
Sounds wrong here in standard Portuguese; singular countable nouns almost always need an article or a determiner.

So um is used to express a general idea: a teacher of that type can have that effect.

Why are pequeno and grande before the nouns (um pequeno erro, um grande falhanço) and not after them?

In Portuguese, adjectives can go before or after the noun, but the position often changes the nuance:

Size adjectives like pequeno and grande commonly come before the noun when they have a more subjective, evaluative, or intensifying meaning.
- um pequeno erro
  = literally a small mistake, but often feels like a minor / slight mistake.
- um grande falhanço
  = a big failure, also strongly evaluative (a major/big-time failure).
After the noun, they tend to sound more neutral and literal:
- um erro pequeno
  = a mistake that is physically or objectively small (more descriptive, less idiomatic here).
- um falhanço grande
  is possible but less usual; it sounds more clunky and less idiomatic than um grande falhanço.

In this sentence, putting pequeno and grande before the nouns sounds more natural and expressive.

What exactly is num, and how is it different from em um or no?

num is a contraction:

em + um → num

It literally means in a / into a.

In this sentence:

transformar um pequeno erro num grande falhanço
= to turn a small mistake into a big failure

Why num and not no?

no = em + o = in the / into the
That would be transformar … no grande falhanço (into the big failure), referring to a specific failure.
num keeps it indefinite: into a big failure (in general).

You could technically say em um instead of num, but in natural speech and writing, the contraction num is strongly preferred whenever possible.

Why is pode transformar in the present tense? Could we say poderá transformar?

pode transformar is the present of possibility/ability and is used for general truths:

Um professor demasiado severo pode transformar…
= A teacher who is too strict can turn… (this is something that can generally happen)

It’s not about a specific future event; it’s a general statement.

poderá transformar is the future (he will be able to / might be able to), and would sound more like a prediction about some particular case. For a general observation, Portuguese very often uses the present tense, just as here.

What is the difference between erro, engano, and falha? Could they replace erro here?

All three can mean some kind of mistake, but they’re used differently:

erro
The most general word for mistake / error. Works in almost any context (school, work, math, life).
engano
Often involves misunderstanding, confusion, or choosing the wrong thing by accident.
- Foi um engano. = It was a misunderstanding / I dialed the wrong number, etc.
falha
More like fault, flaw, lapse, failure of a system/person.
- falha técnica = technical failure
- falha de memória = memory lapse

In this sentence, erro is the best, most natural word. You could say um pequeno engano, but it would slightly shift the nuance toward a misunderstanding rather than a generic mistake. falha would feel odd here.

What is the nuance of falhanço compared to fracasso or falha?

All relate to failure, but with different feel:

falhanço
Colloquial, vivid word for a big flop, a real failure, a mess-up. Often carries a bit of emotional weight or drama.
- O projeto foi um falhanço. = The project was a total flop.
fracasso
More neutral and sometimes more formal.
- O projeto foi um fracasso. = The project was a failure.
  You could use fracasso here and it would be correct and quite natural:
  …num grande fracasso.
falha
Usually refers to fault, flaw, lapse, and not the whole big outcome being a flop.

In this sentence, falhanço makes the contrast stronger and more vivid: from a small error to a major flop.

Can we say pode fazer de um pequeno erro um grande falhanço instead of pode transformar um pequeno erro num grande falhanço?

Yes, that sentence is grammatically correct and understandable:

pode fazer de um pequeno erro um grande falhanço
= can make a small mistake into a big failure

However:

transformar … num … is very idiomatic and compact for turning X into Y.
fazer de X Y is also correct but feels slightly more formal/bookish here and is less common in everyday speech in this kind of phrase.

So the original pode transformar um pequeno erro num grande falhanço sounds more natural and fluent.

Why are all the adjectives masculine and singular (severo, pequeno, grande)?

In Portuguese, adjectives must agree in gender and number with the noun they describe.

Nouns here:

um professor → masculine singular
um pequeno erro → masculine singular
um grande falhanço → masculine singular

So the adjectives must match:

professor → severo (not severa)
erro → pequeno
falhanço → grande (same form for masc. and fem. in the singular)

If we changed the nouns to feminine, everything would change:

uma professora demasiado severa
uma pequena falha
uma grande derrota

How do you pronounce falhanço, especially the lh, an, and ç?

Approximate European Portuguese pronunciation: [fa-ʎÂN-soo] (rough guide).

Piece by piece:

fa- → like fa in father.
lh → a single consonant, similar to the lli sound in million (British), or Spanish ll in llama. So falha- ≈ fa-lya.
an (before a consonant) is nasal in European Portuguese. It’s not exactly an as in ant; it’s more like saying an but letting air go through your nose, closer to French an.
ç → always like s in see.
Final -o in European Portuguese is usually pronounced like u in put or oo in foot, so roughly -soo.

So you might approximate it in English as fa-lyan-soo, with a nasal yan.

How do you pronounce erro, and what does the rr do?

Approximate European Portuguese pronunciation: [EH-hoo] (with a strong h).

Details:

e → like e in bed, but a bit more closed.
rr between vowels is a strong guttural sound, similar to:
- the h in many English accents saying house very strongly, or
- the French r in Paris.
Final -o again is often like oo in foot (not like go).

So erro is roughly EH-hoo, with a strong h-like sound in the middle.