Puella librum amissum rursus invenit et magistrae ostendit.

Latin often leaves subject pronouns unstated when they are easy to understand from the verb ending or from a noun already present.

Here, puella names the subject, and both invenit and ostendit are third-person singular verb forms, so the sentence already tells you the girl is doing the actions. A separate she would be unnecessary unless Latin wanted special emphasis.

Librum is the accusative singular form of liber, and it is used because the book is the direct object of invenit.

In other words, the girl is doing the action, and the book is what she finds. In Latin, direct objects usually go in the accusative case.

• liber = nominative, book as subject
• librum = accusative, book as direct object

Because amissum describes librum, and Latin adjectives must agree with the nouns they describe in gender, number, and case.

So:

• librum = masculine, singular, accusative
• amissum = masculine, singular, accusative

Even though English does not change lost, Latin does. The ending shows that amissum goes with librum, not with puella.

It is the perfect passive participle of amittere, and here it is being used like an adjective.

Literally, it has the sense of having been lost, but in smooth English it is usually just translated as lost. This is very common in Latin: a participle can function as an adjective and describe a noun.

Here magistrae is dative singular, meaning to the teacher.

The verb ostendere often works with:

• a direct object: the thing shown
• a dative: the person it is shown to

So the structure is basically:

alicui aliquid ostendere = to show something to someone

That is why Latin uses magistrae, not magistram.

It is true that -ae can mean more than one thing in first-declension nouns, but in this sentence the verb and context make dative singular the right choice.

Because Latin often leaves out a word when it is already obvious from the context.

The understood object of ostendit is still librum amissum. So the sense is:

The girl found the lost book again and showed it to the teacher.

Latin does not need to repeat the object if it is clear.

Because et joins the two verbs, and no new subject is introduced.

So the natural reading is:

• puella ... invenit
• et ... ostendit

The subject remains puella for both verbs. If Latin wanted a different person to do the second action, it would normally make that clear with another noun or pronoun.

Rursus is an adverb, meaning again or back.

It modifies the verb invenit, telling you how the finding happened. Since it is an adverb, it does not change its form to match any noun. Unlike amissum, it does not agree with anything.

In Latin spelling without extra marks, these forms can be ambiguous.

• invenit can mean finds or found
• ostendit can mean shows or showed

Usually you know which is meant from the context, from the translation given, or from a passage around it.

A small detail: in texts that mark long vowels, the perfect of invenit may appear as invēnit, which helps distinguish it from the present. But ostendit is often identical in spelling in both present and perfect, so context matters a lot.

Latin word order is much more flexible than English word order because the endings show what each word is doing.

English depends heavily on order:

• The girl found the book is different from The book found the girl

Latin depends more on case endings:

• puella shows the subject
• librum shows the direct object
• magistrae shows the indirect object

Because of that, Latin can arrange words for style, emphasis, or rhythm. This sentence has a very natural Latin feel, with the verbs coming later in their clauses.