Learn Hardcore Russian: Мой добрый папа редко бывает строгим, но иногда сердится, когда я делаю много ошибок. - My kind dad is rarely strict, but sometimes he gets angry when I make many mistakes.

Because it’s masculine, it takes masculine forms:
- мой папа (my dad), not моя папа
- добрый папа (kind dad), not добрая папа
The ending -а doesn’t always mean the noun is feminine. A small group of masculine nouns referring to people use it:
- папа, дядя (uncle), мужчина (man), юноша (young man)

So: мой (masc.), добрый (masc.), папа (masc.) all agree in gender.

What’s the difference between мой добрый папа and мой папа добрый?

Both are grammatically correct but feel different:

Мой добрый папа
- Neutral, typical order: determiner → adjective → noun
- Sounds like “my kind dad” as a fixed description, almost like a little title.
Мой папа добрый
- More like “my dad is kind” (statement about him).
- This is a full sentence with папа as the subject and добрый as the predicate adjective (like Он добрый).

In your sentence, Мой добрый папа works as a single noun phrase (subject) meaning “My kind dad…”, not as “My dad is kind”.

What exactly does редко бывает строгим mean? Why not just редко строгий?

Редко бывает строгим literally means “is strict rarely / is rarely strict,” with a nuance of “from time to time / on some occasions.”

бывает is the 3rd person singular of бывать, related to быть (“to be”) but with a habitual / occasional meaning: “tends to be,” “is at times,” “gets.”
строгим is in the instrumental case after a form of быть / бывать.

Compare:

Он строгий. – “He is strict.” (a general, permanent trait)
Он редко бывает строгим. – “He is rarely strict / He rarely acts strict.” (not his usual state, just sometimes)

Редко строгий on its own sounds incomplete in this context; you normally need a verb:
Он редко бывает строгим or Он редко бывает строгим папой, etc.

Why is it строгим (instrumental) and not строгий (nominative) after бывает?

With быть / бывать used as a full verb (not just the “zero” present есть), Russian often uses the instrumental for predicate nouns and adjectives, especially to describe a temporary or changeable state.

Он строгий. – simple statement, present time, general characteristic; no verb быть is used.
Он бывает строгим. – he sometimes is / can be strict; this is more like a role or temporary state, so строгим (instrumental) is natural.

Rough rule of thumb:

Nominative predicate (строгий): stable quality, simple describing.
Instrumental predicate (строгим): status, role, or temporary state, often after explicit был / будет / бывает.

So редко бывает строгим nicely suggests “is strict only occasionally.”

Why is there a comma before но in ..., но иногда сердится ...?

Но (“but”) joins two independent clauses here:

Мой добрый папа редко бывает строгим – complete clause (subject + verb).
(Он) иногда сердится, когда я делаю много ошибок – another clause; the subject он is understood.

In Russian, when но connects two full clauses, you put a comma before it:

Он устал, но продолжал работать.
Она молчит, но всё понимает.

So the comma before но is mandatory here.

Why is the subject omitted in но иногда сердится? Where is он?

The subject он (“he”) is understood from the previous clause (Мой добрый папа).

Russian often omits pronouns if the subject is already clear from context, especially in coordinated clauses:

Мой брат любит музыку и играет на гитаре.
(Not и он играет, though that’s also possible; just not necessary.)

Here:

First clause: Мой добрый папа редко бывает строгим.
Subject: папа
Second clause: (Он) иногда сердится...
The same subject continues, so он is naturally dropped.

You could say ...но он иногда сердится... to emphasize he a bit more, but it’s not required.

What does сердится mean exactly, and why does it end in -ся?

Сердится is the 3rd person singular of сердиться – “to get angry,” “to be angry.”

сердиться = сердить + -ся.
The -ся ending makes the verb reflexive or, more broadly, “middle voice”.
You can think of it as “to become angry (oneself)” / “to be in a state of anger.”

It’s similar to other reflexive/emotional verbs:

злиться – to be angry, mad
обижаться – to take offense, to feel hurt
смеяться – to laugh

So папа сердится ≈ “Dad gets angry / Dad is (gets) upset / mad.”

What’s the difference between сердится and злится?

Both mean “to be angry,” but there’s a nuance:

сердиться – milder, “to be annoyed / upset / cross / angry.”
Often used for everyday irritation, especially with children:
Мама сердится, когда я опаздываю.
злиться – stronger, “to be mad / furious / really angry.”
More intense emotion:
Он сильно злится на начальника.

In your sentence, сердится fits well: a “kind dad” who sometimes gets annoyed when you make many mistakes. Using злится would make him sound more seriously angry.

Why is the present tense used in когда я делаю много ошибок if we’re talking about a general situation, not one specific time?

In Russian, the present tense is regularly used to describe general, repeated, or habitual actions, especially in когда (“when”) clauses:

Когда я устал, я пью кофе. – “When I’m tired, I drink coffee.”
Когда он нервничает, он много курит.

So:

когда я делаю много ошибок = “when I make a lot of mistakes (whenever that happens).”

Even though it’s general/habitual, Russian still uses the simple present tense here.

Why is it делаю (imperfective) and not сделаю (perfective)?

Делать / сделать differ in aspect:

делать (imperfective): process, repeated/habitual, “to be doing / to do in general.”
сделать (perfective): one completed action, “to do / to finish doing (once).”

In когда я делаю много ошибок, we’re talking about a repeated, ongoing pattern:

Whenever I tend to be making many mistakes (in general).

If you used perfective:

когда я сделаю много ошибок
This would sound like “when I have made a lot of mistakes (on a particular occasion)” – a single completed event, not a general habit.

So imperfective делаю is the natural choice for describing a habitual trigger for his anger.

Why is it много ошибок and not много ошибки or много ошибках?

After quantifiers like много (“a lot of”), Russian uses the genitive case:

много воды – a lot of water
много людей – many people
много ошибок – many mistakes

Here:

Base noun: ошибка (a mistake)
Genitive plural: ошибок

So the pattern is:

много + [genitive singular or plural]
For countable nouns in plural: много ошибок (genitive plural).

Много ошибки or много ошибках are ungrammatical in standard Russian.

Could we change the word order, for example to Мой добрый папа бывает редко строгим or иногда он сердится? Does it change the meaning?

Russian word order is relatively flexible, but it affects emphasis.

Редко бывает строгим vs бывает редко строгим

Мой добрый папа редко бывает строгим (original)
Neutral, natural order; light emphasis on редко.
Мой добрый папа бывает редко строгим
Still understandable, but the adverb sounds a bit more marked; you’re stressing that the “being strict” happens rarely.

Both are grammatically correct; the original is the most typical.

Иногда сердится vs иногда он сердится vs он иногда сердится

(Он) иногда сердится – neutral, adverb иногда has normal emphasis.
Иногда он сердится – slight emphasis on иногда (“sometimes he (of all people) gets angry”).
Он иногда сердится – very common; similar to the first but with explicit он.

All these options are correct; the meaning stays the same, but the rhythm and focus shift a little.

Can we drop мой and just say Добрый папа редко бывает строгим?

You can grammatically say Добрый папа редко бывает строгим, but:

Without мой, it sounds less like “my dad” and more like:
- “A kind dad is rarely strict” (a general statement about “a kind father”)
- Or the listener must already know which dad you mean from context.

Мой добрый папа clearly marks that you are talking about your own father, which is the most natural in this personal, emotional sentence.