המורה כתבה הערה קצרה במחברת שלי.

By itself, המורה can refer to either a male teacher or a female teacher. The noun מורה in the singular does not clearly show gender in everyday unpointed spelling.

The ה־ at the beginning simply means the, so המורה = the teacher.

You know from the verb כתבה.

In the past tense, Hebrew verbs show gender in the singular:

• כתב = he wrote
• כתבה = she wrote

So המורה כתבה means the teacher wrote, with the teacher understood as female.

Hebrew has no indefinite article. There is no separate word for a or an.

So:

• הערה can mean a note or a comment
• הערה קצרה = a short note/comment

If the noun were definite, Hebrew would use ה־:

• ההערה הקצרה = the short note

In Hebrew, adjectives usually come after the noun they describe.

So:

• הערה קצרה = literally note short
• natural English order: a short note

This is the normal pattern in Hebrew:

• ספר מעניין = an interesting book
• ילדה קטנה = a small girl

Because adjectives in Hebrew must agree with the noun in:

• gender
• number
• definiteness

Here, הערה is:

• feminine
• singular
• indefinite

So the adjective must match:

• קצרה = feminine singular
• קצר = masculine singular

Compare:

• הערה קצרה = a short note
• ספר קצר = a short book

Because את is used before a definite direct object, not an indefinite one.

Here the object is הערה קצרה, which is indefinite: a short note. So there is no את.

Compare:

• המורה כתבה הערה קצרה = The teacher wrote a short note
• המורה כתבה את ההערה הקצרה = The teacher wrote the short note

במחברת is made of:

• ב־ = in
• מחברת = notebook / exercise book

So במחברת means in a notebook or in the notebook, depending on context.

In Hebrew, short prepositions like ב־ (in), ל־ (to), and כ־ (as/like) are usually attached directly to the next word.

That is the normal Hebrew pattern.

Hebrew usually expresses possession with:

• noun + שלי / שלך / שלו / שלה etc.

So:

• המחברת שלי = my notebook
• literally: the notebook of mine

English puts my before the noun, but Hebrew usually puts שלי after it.

Because the preposition ב־ and the definite article ה־ combine.

So underlyingly:

• ב + המחברת שלי becomes
• במחברת שלי

In everyday Hebrew spelling without vowel marks, the ה often disappears after these attached prepositions.

A useful thing to know is that unpointed במחברת can look the same whether the meaning is:

• in a notebook or
• in the notebook

Here, שלי makes it clear that the meaning is definite: in my notebook.

Yes. This is a very natural word order:

• המורה = subject
• כתבה = verb
• הערה קצרה = direct object
• במחברת שלי = prepositional phrase

So the structure is basically:

Subject + Verb + Object + Place

Hebrew can sometimes use other word orders, but this sentence is completely standard and straightforward.