Mi profesora corrigió el encabezado y añadió una nota al final de la página para aclarar la duda.

In Spanish, possessive adjectives like mi, tu, su, nuestro usually go before the noun:

• mi profesora = my teacher
• tu libro = your book

The longer form (mío, mía, tuyos, nuestra, etc.) usually comes after the noun and is more emphatic or contrastive:

• la profesora mía = my teacher (but with extra emphasis, and less neutral here)

So Mi profesora is the normal, natural choice.

Both are in the preterite tense, third person singular, because the subject is mi profesora and the sentence describes completed actions in the past.

• corrigió = she corrected
• añadió = she added

The teacher did two finished things:

1. she corrected the heading
2. she added a note

That is exactly the kind of situation where Spanish commonly uses the preterite.

This is a very common question.

• corrigió = she corrected
  This presents the action as completed
• corregía = she was correcting / used to correct
  This presents the action as ongoing, habitual, or background information

In your sentence, the teacher finished correcting the heading, so corrigió is the right choice.

Compare:

• Mi profesora corrigió el encabezado.
  She corrected the heading.
• Mi profesora corregía exámenes mientras yo estudiaba.
  My teacher was correcting exams while I was studying.

The accent marks show the correct stress and also help distinguish these past-tense forms.

• corrigió
• añadió

These are third person singular preterite forms of verbs ending in -ir:

• corregir → corrigió
• añadir → añadió

Without the written accent, the stress pattern would be wrong. In Spanish spelling, these forms require the accent.

Not exactly.

Encabezado usually means heading or header, something at the top of a page, section, or document.

Título means title.

Sometimes they can be similar in English depending on context, but they are not always interchangeable.

For example:

• el título del libro = the title of the book
• el encabezado del documento = the heading/header of the document

So in this sentence, encabezado suggests a heading rather than the main title.

Spanish uses articles much more often than English.

Here, el encabezado means the heading—a specific heading that both speaker and listener can identify from context.

Spanish normally prefers the article in cases like this:

• corrigió el encabezado
• cerró la puerta
• abrió el libro

English sometimes drops articles in certain expressions, but Spanish usually keeps them.

Yes, both can mean added, but añadir is very common and natural, especially in Spain.

• añadió una nota = she added a note
• agregó una nota = she added a note

In many varieties of Spanish, both are understood, but añadir often sounds more standard or natural in Spain in this kind of written/academic context.

It means at the end of the page.

Breakdown:

• a + el = al
• final = end
• de la página = of the page

So:

• al final de la página = at the end of the page

This is a very common expression in Spanish.

Examples:

• al final del libro = at the end of the book
• al final de la clase = at the end of the class

Because al final is the normal idiomatic expression for at the end.

• al final de la página = at the end of the page

Using en el final is usually unnatural here.

A useful pattern to remember:

• al principio de... = at the beginning of...
• al final de... = at the end of...

So you should learn al final de as a fixed expression.

Para + infinitive is one of the most common ways to express purpose in Spanish.

So:

• para aclarar la duda = to clarify the doubt / in order to clear up the question

This answers why she added the note.

More examples:

• Estudio para aprender. = I study to learn.
• Lo hice para ayudarte. = I did it to help you.

Aclarar una duda is a very natural Spanish expression. It means to clear up a doubt/question/uncertainty.

Other verbs are possible, but they are slightly different:

• aclarar una duda = to clarify / clear up a doubt
• resolver una duda = to resolve a doubt
• contestar una pregunta = to answer a question

Notice that duda is not exactly the same as pregunta.

So:

• aclarar la duda sounds very idiomatic here
• contestar la duda would not be the normal combination

Literally, duda means doubt, but in learning or academic contexts it often means something closer to:

• question
• uncertainty
• point of confusion

So aclarar la duda often means:

• clear up the confusion
• answer the question
• clarify the uncertainty

A learner should not always translate duda as English doubt word-for-word.

Using la duda suggests it is a specific doubt/question already known from the context.

• una duda = a doubt / a question
• la duda = the doubt / the question

In this sentence, the note was added to clarify the particular issue being discussed, so la duda makes sense.

In Spanish, as in English, you normally do not use a comma before y when linking two simple actions with the same subject.

So this is standard:

• Mi profesora corrigió el encabezado y añadió una nota...

A comma might appear only in special cases, such as:

• a parenthetical interruption
• a change in structure
• avoiding ambiguity

But in this sentence, no comma is needed.

Yes, Spanish often omits subject pronouns, but here the sentence uses the full noun phrase Mi profesora because it introduces who did the actions.

After that, Spanish does not need to repeat the subject:

• Mi profesora corrigió el encabezado y añadió una nota...

You could not simply remove it unless the context already made the subject clear:

• Corrigió el encabezado y añadió una nota...

That would mean She corrected the heading and added a note..., but only if we already know who she is.

The given word order is very natural:

• Mi profesora corrigió el encabezado y añadió una nota al final de la página para aclarar la duda.

Spanish word order is somewhat flexible, but changes can affect emphasis.

For example:

• Mi profesora añadió una nota al final de la página para aclarar la duda.
• Para aclarar la duda, mi profesora añadió una nota al final de la página.

Both are possible, but the original is the most straightforward, neutral version.

Because Spanish normally uses the article here.

• la página = the page
• al final de la página = at the end of the page

Spanish often includes articles in places where English may sound shorter or more compact.

So de página by itself would not be correct in this sentence.

• añadir is the infinitive: to add
• añadió is the preterite, third person singular: he/she/it added

Same idea with:

• corregir = to correct
• corrigió = he/she corrected

A useful thing to notice is that many Spanish verbs change form quite a lot between the infinitive and the past tense, so it is worth learning both together.