Learn Hardcore Russian: Я сам повторю это правило.

Without сам: Я повторю это правило. – I’ll repeat this rule. (neutral)
With сам: Я сам повторю это правило. – I’ll repeat this rule *myself (I’ll be the one to do it).*

The emphasis is usually:

Either I, not another person (e.g. not the teacher, not my friend)
Or that I don’t need help / I’ll take responsibility myself.

It does not automatically mean “alone in the room with nobody present”; it’s more about who takes the action and whose initiative it is.

Why is it сам and not сама / само / сами?

Сам agrees in gender and number with the subject я (and therefore with the speaker):

A man speaking: Я сам повторю это правило.
A woman speaking: Я сама повторю это правило.
About a neuter noun (rare with я, but e.g. with оно): оно само
Plural: мы сами, они сами

So the form changes like this:

Masculine: сам
Feminine: сама
Neuter: само
Plural: сами

Where can сам go in the sentence? Is Я сам повторю это правило the only correct order?

Russian word order is flexible. All of these can be correct, but the emphasis shifts:

Я сам повторю это правило.
– Neutral, standard; focuses on I myself as the doer.
Я повторю это правило сам.
– Stronger focus on сам at the end: I’ll repeat this rule *myself (not you / not anybody else).*
Сам я повторю это правило.
– Sounds a bit more “spoken” or emphatic, highlighting сам я: I, myself, will repeat this rule.

All are possible in the right context. The version you have is the most typical neutral one.

Why is the verb повторю and not буду повторять?

Both are future, but they differ in aspect:

Повторю – future of the perfective verb повторить
- Focus on a single, completed action: I will repeat (once / get it done).
Буду повторять – analytical future of the imperfective verb повторять
- Focus on process, repetition, or duration: I will be repeating / I will keep repeating.

So:

Я сам повторю это правило. – I will (once) repeat this rule myself, get it done.
Я сам буду повторять это правило. – I will keep repeating this rule myself (over and over).

In your sentence, the point is usually a single act of repetition, so повторю is natural.

How is the future form повторю formed?

Повторю is the 1st person singular future of the perfective verb повторить.

Pattern of conjugation (future, perfective):

я повторю – I will repeat
ты повторишь – you (sg) will repeat
он / она / оно повторит – he / she / it will repeat
мы повторим – we will repeat
вы повторите – you (pl/formal) will repeat
они повторят – they will repeat

The stress in повторю is on the last syllable: повторю.

Why is it это правило and not этот правило?

Because правило is neuter (ending in -о in nominative singular).

The demonstrative adjective этот / эта / это / эти agrees with the gender and number of the noun:

Masculine: этот стол (this table)
Feminine: эта книга (this book)
Neuter: это правило (this rule)
Plural (for any gender): эти правила (these rules)

So with правило (neuter), the correct form is это.

What case is это правило in, and why does it look like the dictionary form?

Это правило is in the accusative case, because it is the direct object of the verb повторю (repeat what? – this rule).

For inanimate neuter nouns like правило, the accusative singular form is identical to the nominative singular:

Nominative: это правило – this rule (as a subject)
Accusative: Я повторю это правило. – I’ll repeat this rule.

So it looks like the dictionary form because neuter inanimate nouns do not change in shape from nominative to accusative.

Could I say Я буду повторять это правило сам instead? What’s the difference?

Yes, you can. The differences:

Aspect and meaning of the verb
- Я сам повторю это правило. – One, completed act of repetition.
- Я буду повторять это правило сам. – Repeated or ongoing action: I will keep repeating this rule myself / I’ll be the one regularly repeating it.
Position of сам
- сам right after я: more neutral emphasis on who does it.
- сам at the end (…правило сам) – sometimes feels more contrastive: I’ll be the one doing it (not you).

So your alternative is correct, but it describes a more continuous or repeated action.

Can I drop я and just say Сам повторю это правило?

Yes, that is possible in the right context, especially in spoken Russian.

Сам повторю это правило. – I’ll repeat this rule myself.

In Russian, subject pronouns (like я) are often dropped because the verb ending already shows the person. Here, повторю clearly indicates “I”.

However:

With both я and сам, you get a fuller, slightly more explicit sentence: Я сам повторю это правило.
Without я, сам stands in first position and gets more emphasis: I myself will do it.

Both are grammatically correct.

Does сам mean “by myself” in the sense of “alone”?

Not necessarily. Сам is primarily about:

Who is responsible (I myself, not someone else)
Personal involvement or initiative

Sometimes in context it can imply “I don’t need help / I’ll manage alone”, but grammatically it is about identity, not physical isolation.

Compare:

Я сам повторю это правило. – I’ll be the one who repeats it (not you).
Я один повторю это правило. – I will repeat this rule alone (no one else with me).

Один / одна clearly expresses “alone”; сам / сама expresses “myself / personally”.

Is правило singular or plural here? How would the plural look?

In Я сам повторю это правило, правило is singular: this rule.

The plural of правило is правила:

Nominative plural: эти правила – these rules
Accusative plural (inanimate): also эти правила

Example with plural object:

Я сам повторю эти правила. – I will repeat these rules myself.

Is there a reflexive form like повторюсь? Why don’t we use it here?

There is a reflexive verb повториться, but it has a different meaning:

повторить (что?) – to repeat something
повториться – to happen again, to be repeated (often about an event or situation)

Examples:

Я повторю это правило. – I’ll repeat this rule.
История повторилась. – The story repeated itself / History repeated itself.

In your sentence, you need a transitive verb that takes a direct object (the rule), so повторю (not повторюсь) is correct.

Why is я lowercase in Russian, unlike “I” in English?

In Russian, the first person singular pronoun я is written with a lowercase letter in the middle of a sentence:

Я сам повторю это правило.
Он сказал, что я повторю это правило.

It is capitalized only when it appears at the beginning of a sentence (like any other word in that position), not because it is a pronoun. This is different from English, where I is always capitalized.