Learn Hardcore Portuguese (Portugal): Uma atividade simples pode ser mais eficaz do que um plano complexo. - A simple activity can be more effective than a complex plan.

atividade is a feminine noun → it takes the feminine singular article uma.
- uma atividade = a/an activity
plano is a masculine noun → it takes the masculine singular article um.
- um plano = a plan

So you always have to learn the gender of each noun, because it affects not only articles (um/uma, o/a) but also adjectives and pronouns around it.

Why is simples after atividade, when in English the adjective comes before the noun?

In Portuguese, the default position of most adjectives is after the noun:

uma atividade simples = a simple activity
um plano complexo = a complex plan

Some adjectives can go before or after the noun, sometimes with a slight change in meaning or emphasis (e.g. um grande homem vs um homem grande). But for a neutral, descriptive sentence like this, putting the adjective after the noun is the most natural pattern to follow as a learner:

noun + adjective → atividade simples, plano complexo

Why doesn’t simples change for masculine/feminine or singular/plural?

simples is one of those adjectives that are invariable in gender:

feminine singular: uma atividade simples
masculine singular: um plano simples

For the plural, the written form stays simples, though you pronounce the final -s:

feminine plural: atividades simples
masculine plural: planos simples

So simples is the same form for all genders and numbers; agreement is only shown by the article and the noun, not by the adjective.

What does pode ser literally mean here, and why do we use poder?

pode ser is:

pode = 3rd person singular of poder (to be able to / can / may)
ser = to be

So pode ser literally means “can be” or “may be”.

In this sentence, it expresses possibility or potential:

Uma atividade simples pode ser mais eficaz…
= A simple activity *can be / may be more effective…*

You use poder+infinitive to say what is possible, permitted, or potentially true, not what is always or necessarily true.

Why is ser used in pode ser mais eficaz, and not estar?

In Portuguese, ser and estar both translate as “to be”, but:

ser is used for more permanent, essential, or characteristic qualities.
estar is used for temporary states or conditions.

Here we’re talking about how a simple activity, in general, can be more effective than a complex plan. That’s an abstract, typical characteristic, not a temporary condition.

So we use ser:

Uma atividade simples pode ser mais eficaz…
= A simple activity can be (as a general characteristic) more effective…

If we were describing a temporary state (e.g. Today this plan is being effective), then we could say está a ser eficaz in European Portuguese.

How does the comparison mais eficaz do que work? What’s the structure?

The standard comparative structure in Portuguese is:

mais + adjective + (do) que = more … than …

So:

mais eficaz do que um plano complexo
= more effective than a complex plan

Breaking it down:

mais = more
eficaz = effective / efficient
do que = than (literally “of the that/which”)

You can use the same pattern with other adjectives:

mais rápido do que = faster than
mais interessante do que = more interesting than

What exactly is the do in do que?

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

de + o → do

So literally:

mais eficaz do que = “more effective of the that/which”

In modern Portuguese, do que has become a fixed comparative connector and is normally understood simply as “than”:

mais … do que … = more … than …

Can I say mais eficaz que um plano complexo instead of mais eficaz do que? Is there any difference?

Yes, you can. Both are correct:

mais eficaz do que um plano complexo
mais eficaz que um plano complexo

In everyday European Portuguese, que without do is very common and fully acceptable. do que is a bit more traditional or formal in some people’s perception, but in practice both are widely used and you will hear and read both forms.

For you as a learner, it’s fine to use either. Just be consistent inside a single sentence.

I’ve seen actividade with a c before. Why is it atividade here? Is that a Portugal vs Brazil difference?

This is mainly about spelling reform, not about meaning:

Before the 1990 Orthographic Agreement, European Portuguese used actividade, objecto, etc.
With the reform, many silent consonants were removed, so now the standard spelling (in both Portugal and Brazil) is atividade, objeto, etc.

In Portugal today, in modern writing, you’ll normally see atividade (without c), even though older texts and people educated before the reform may still write actividade.

Pronunciation in European Portuguese didn’t change: the c in actividade was already silent.

How do you pronounce the sentence in European Portuguese?

In IPA (European Portuguese):

/u.mɐ ɐ.ti.vi.ˈðað(ɨ) ˈsĩ.plɨʃ ˈpɔ.ðɨ seɾ mɐjʃ e.fi.ˈkaʃ du ˈkɛ ũ ˈplɐ.nu kõ.ˈplɛk.su/

Very rough English-like approximation (not exact, just to guide your ear):

Uma → “OO-muh” (short final “uh”)
atividade → “uh-chee-vee-DAH-d(uh)” (final vowel very reduced)
simples → “SEEN-plsh” (final -s like “sh”)
pode → “POH-d(uh)”
ser → “sehr” (r like a soft guttural or uvular sound)
mais → “maish”
eficaz → “eh-fee-KASH” (final -z like “sh”)
do que → “du KEH”
um → nasal “u” (“oo” with the sound going through your nose)
plano → “PLUH-nu”
complexo → “kõm-PLÉK-su”

European Portuguese reduces a lot of unstressed vowels and often turns final s into a sh sound.

What are the gender and agreement patterns for eficaz and complexo?

eficaz
- Same form for masculine and feminine singular:
  - um plano eficaz, uma atividade eficaz
- Plural: eficazes (for both genders):
  - planos eficazes, atividades eficazes
complexo
- Masculine singular: complexo → um plano complexo
- Feminine singular: complexa → uma atividade complexa
- Masculine plural: complexos → planos complexos
- Feminine plural: complexas → atividades complexas

So eficaz changes only for number, while complexo changes for both gender and number.

Could I say Uma simples atividade pode ser mais eficaz… instead of Uma atividade simples? Does it change the meaning?

Yes, you can change the order, but there is a subtle nuance:

Uma atividade simples
→ neutral description: an activity that is simple (not complicated).
Uma simples atividade
→ often adds a nuance like “just a simple activity / merely a simple activity”, highlighting how little or basic it is.

In your original sentence:

Uma simples atividade pode ser mais eficaz do que um plano complexo.
suggests: Even just a simple activity (nothing fancy) can be more effective than a complex plan.

Both are correct; adjective after the noun is the safer, more neutral choice, but simples before the noun is very natural in this type of contrastive, almost “moral lesson” sentence.