Magistra dicit vitia parva facile crescere, nisi statim corriguntur.

Because after a verb of saying like dicit, Latin very often uses an indirect statement construction.

That construction is:

• a verb of saying, thinking, knowing, etc.
• • an accusative subject
• • an infinitive

So magistra dicit vitia parva facile crescere literally works like:

• magistra dicit = the teacher says
• vitia parva = small faults
• crescere = to grow

In smoother English, we usually translate it with that:

• The teacher says that small faults grow easily.

Latin normally uses the infinitive here where English uses that + verb.

In an indirect statement, the logical subject is put in the accusative, not the nominative.

So even though vitia parva are the things that grow, Latin treats them as the subject of the infinitive crescere, and the subject of an infinitive in this construction goes into the accusative.

That is why you get:

• vitia parva crescere = small faults to grow
  or more naturally, that small faults grow

This is one of the most important Latin patterns to get used to.

Because parva has to agree with vitia.

Vitia is:

• neuter
• plural
• accusative

So the adjective must also be:

• neuter
• plural
• accusative

That gives parva.

So:

• vitium parvum = a small fault
• vitia parva = small faults

The adjective agrees in gender, number, and case.

Vitia is the plural of vitium, a neuter noun.

It can mean things like:

• faults
• defects
• vices
• bad habits

In this sentence, faults or bad habits is probably the most natural sense. The idea is that even small moral or personal faults can become bigger if they are not corrected right away.

Because the regular adverb from facilis is facile.

So:

• facilis = easy
• facile = easily

It modifies crescere, telling us how the faults grow.

So facile crescere means:

• to grow easily

This is just something to learn as part of the vocabulary pattern of facilis.

Nisi means unless or sometimes if not.

Here it introduces the condition under which the small faults will grow easily:

• vitia parva facile crescere, nisi statim corriguntur
• small faults grow easily, unless they are corrected at once

So the sentence means that growth happens except in the case where they are corrected immediately.

Because the meaning is unless they are corrected, not unless they correct.

Corriguntur is:

• present
• passive
• indicative
• third person plural

from corrigo, corrigere, correxi, correctum = correct, set right

So:

• corrigunt = they correct
• corriguntur = they are corrected

The passive is needed because the faults are receiving the action.

The subject is understood to be vitia parva.

Latin often does not repeat a subject when it is already clear from context. So after hearing vitia parva, the listener naturally understands that corriguntur refers to those same faults.

In other words, the full sense is:

• nisi vitia parva statim corriguntur

But Latin does not need to repeat vitia parva.

Because its understood subject, vitia parva, is plural.

Since vitia means faults rather than fault, the verb must also be plural:

• corrigitur = it is corrected
• corriguntur = they are corrected

So the plural verb agrees with the plural subject.

The sentence expresses a general truth or general principle, not a one-time event.

So Latin uses the present:

• dicit = says
• crescere = to grow / grow
• corriguntur = are corrected

The present infinitive crescere shows action that is contemporaneous with dicit in the indirect statement. In simpler terms, the teacher says that this is what happens: small faults grow easily unless they are corrected immediately.

It is quite normal for Latin.

Latin word order is much freer than English word order, because the endings show how the words function. This sentence is arranged in a very natural Latin way:

• Magistra dicit — main statement first
• vitia parva — subject of the indirect statement
• facile crescere — infinitive phrase
• nisi statim corriguntur — condition added at the end

A very literal English order might sound odd, but in Latin the structure is clear from the endings.

Sometimes Latin can use a quod clause after verbs of saying or feeling, especially in later Latin or in certain contexts. But the classic and very common construction after dicit is the accusative-and-infinitive.

So in this sentence, dicit vitia parva facile crescere is exactly the sort of structure a learner should expect.

It is one of the standard patterns for reporting what someone says.