Learn Hardcore Portuguese (Portugal): Por favor, lembra o Pedro do exame amanhã. - Please remind Pedro about the exam tomorrow.

The normal present-tense form for tu is lembras (“you remind / you remember”).
To form the affirmative imperative for tu, you usually:
- take the present indicative form (lembras)
- drop the final -s → lembra

So:

(tu) lembras = you remind / you remember (statement)
(tu) lembra = remind! (command / request)

Lembre would be the imperative for você / o senhor / a senhora (more formal “you”):

(Você) lembre o Pedro do exame amanhã. = Please remind Pedro of the exam tomorrow. (formal / polite)

Could I say Por favor, lembras o Pedro do exame amanhã instead?

Grammatically, yes, but it would not sound like a request; it would sound like a statement or a yes/no question, depending on intonation:

Por favor, lembras o Pedro do exame amanhã.
→ This is odd: literally “Please, you remind Pedro of the exam tomorrow.” (sounds wrong in context)
Por favor, lembras o Pedro do exame amanhã?
→ “Do you remind Pedro of the exam tomorrow, please?” (a question, not a command)

To ask someone to do it, you normally use the imperative:

Por favor, lembra o Pedro do exame amanhã. (informal “tu”)
Por favor, lembre o Pedro do exame amanhã. (formal “você”)

What is the difference between lembrar and lembrar-se?

They are related but used differently:

lembrar (non‑reflexive) = to remind (someone of something)
Pattern: lembrar alguém de alguma coisa
- Lembra o Pedro do exame. = Remind Pedro of the exam.
- Ela lembrou o João da reunião. = She reminded João about the meeting.
lembrar-se (de) (reflexive) = to remember (something)
Pattern: lembrar-se de alguma coisa
- Lembra-te do exame amanhã. = Remember the exam tomorrow. (you yourself)
- Ela lembra-se do exame. = She remembers the exam.

So:

Lembra o Pedro do exame. → You remind Pedro.
Lembra-te do exame. → You remember the exam.

What is the grammatical pattern of lembrar o Pedro do exame? How do I generalize it?

The core pattern for “remind someone of/about something” in European Portuguese is:

lembrar alguém de alguma coisa

Breaking down the sentence:

lembrar = to remind
o Pedro = the person being reminded (alguém)
do exame = of the exam (de
- o exame)

So you can say:

Lembra o Pedro do exame. = Remind Pedro of the exam.
Lembra a Maria da reunião. = Remind Maria about the meeting.
Lembra os teus pais do aniversário. = Remind your parents about the birthday.

The preposition used is de, not sobre, in this structure.

What exactly does do mean in do exame? Why not just de exame?

Do is a contraction of the preposition de + the masculine singular definite article o:

de
- o exame → do exame

You use it because you are talking about a specific exam (“the exam”), not just any exam.

Compare:

do exame = of the exam (known/specific)
de um exame = of an exam (non‑specific)
de exame (without article) is unusual here; it sounds incomplete or too abstract for this context.

So lembrar alguém do exame literally is “remind someone of the exam.”

Why is it o Pedro and not just Pedro? Do you always put o / a before people’s names?

In European Portuguese, it is very common to use the definite article before a person’s first name, especially when:

you are talking about the person, not speaking directly to them, and
the person is familiar / specific.

So:

O Pedro tem um exame amanhã. = Pedro has an exam tomorrow.
Lembra o Pedro do exame. = Remind Pedro of the exam.

This is normal and sounds natural in Portugal.

Notes:

When you address someone directly, you usually drop the article:
- Pedro, lembra-te do exame amanhã.
In Brazilian Portuguese, the article before first names is less common in standard speech, though you may still hear it in some regions or informal contexts.

Can I change the word order of por favor and amanhã? For example, are these OK?

Lembra o Pedro do exame amanhã, por favor.
Amanhã, por favor, lembra o Pedro do exame.

Yes, those word orders are possible and natural, with small differences in emphasis:

Lembra o Pedro do exame amanhã, por favor.
- Very typical: main request first, por favor at the end for politeness.
- Neutral, everyday tone.
Amanhã, por favor, lembra o Pedro do exame.
- Puts more emphasis on tomorrow (as in “tomorrow, please don’t forget to remind him”).
- Sounds a bit more structured or “careful” speech.
Original:
- Por favor, lembra o Pedro do exame amanhã.
  - Starts with politeness marker por favor, then the request.

All three are grammatically fine. Word order with por favor and time adverbs like amanhã is quite flexible.

How would I say “Please remind me about the exam tomorrow” in European Portuguese? Where does the pronoun go?

For “remind me,” you use the clitic pronoun me attached to the verb:

Por favor, lembra-me do exame amanhã.

Key points (European Portuguese):

In affirmative imperatives, the clitic pronoun typically goes after the verb (enclisis):
- lembra-me (remind me)
- lembra-o (remind him)
- lembra-nos (remind us)
With Por favor at the beginning, you still keep enclisis in European Portuguese:
- Por favor, lembra-me do exame amanhã.

In Brazilian Portuguese, pronoun placement is often different (they would more naturally say Por favor, me lembra do exame amanhã).

How could I make this sentence more formal or polite in Portuguese (Portugal)?

Several options, from slightly to more formal:

Use the formal imperative (você):
- Por favor, lembre o Pedro do exame amanhã.
Use a polite modal verb construction (very common in Portugal):
- Pode lembrar o Pedro do exame amanhã, por favor?
  (“Can you remind Pedro of the exam tomorrow, please?”)
- Podia lembrar o Pedro do exame amanhã, por favor?
  (even more polite: “Could you remind Pedro of the exam tomorrow, please?”)
With explicit formal address:
- Se faz favor, lembre o Pedro do exame amanhã.
- O senhor / A senhora pode lembrar o Pedro do exame amanhã?

All these are polite; using pod(e)/podia or se faz favor is very typical in European Portuguese.

Would this sentence be the same in Brazilian Portuguese, or are there differences?

It’s almost the same, but there are some tendencies:

Article before the name
- EP (Portugal): Lembra o Pedro do exame amanhã. (very natural)
- BP (Brazil): more common without the article in many regions:
  - Lembra Pedro da prova amanhã.
Noun for “exam”
- Portugal: exame is standard.
- Brazil: prova is more common in everyday speech for school/university tests.
Pronoun use
- EP: Lembra o Pedro do exame. / Lembra-o do exame.
- BP: often uses strong pronouns instead of clitics:
  - Lembra ele da prova amanhã.
Pronoun position with “me / te / o” etc.
- EP: Por favor, lembra-me do exame.
- BP: Por favor, me lembra da prova.

So a natural Brazilian version might be:

Por favor, lembra o Pedro da prova amanhã.
or
Por favor, lembra ele da prova amanhã.