Non sum certus discipulos paratos esse, sed magistra dicit eos paratos esse.

I am not sure that the students are ready, but the teacher says that they are ready.

Breakdown of Non sum certus discipulos paratos esse, sed magistra dicit eos paratos esse.

• esse: to be
• discipulus: the student
• non: not
• sed: but
• magistra: the female teacher
• dicere: to say
• eos: them
• certus: sure
• paratus: ready

Questions & Answers about Non sum certus discipulos paratos esse, sed magistra dicit eos paratos esse.

Why is discipulos (accusative) used instead of discipuli (nominative)?

Because discipulos paratos esse is an indirect statement (also called an accusative-and-infinitive construction). In an indirect statement, the “subject” of the reported idea is put in the accusative (discipulos), and the verb is put in the infinitive (esse).
So literally it’s “I am not sure the students (acc.) to be ready (inf.).”

Why does certus take an infinitive clause here—does sum certus trigger an indirect statement like dicit does?

Yes. Latin often expresses “I am sure that … / I am not sure that …” using an accusative + infinitive, especially with expressions like certus sum.
English uses that + finite verb; Latin commonly uses accusative + infinitive.

What exactly is paratos esse—why not just parati sunt?

paratos esse is the infinitive form needed for an indirect statement.

• parati sunt = “they are ready” (a direct statement)
• paratos esse = “(that) they are ready” / “them to be ready” (reported/embedded statement)

So the grammar forces the infinitive.

Is paratos esse “present infinitive” or “perfect infinitive”? It looks like a perfect passive infinitive.

Formally, paratos esse is built like a perfect passive infinitive: paratus (PPP used adjectivally) + esse.
But with paratus meaning ready/prepared, this combination often functions like a state (“to be ready”) rather than emphasizing completed action (“to have been prepared”). Context decides, but in everyday reading it’s usually just “to be ready.”

Why is paratos accusative plural masculine?

Because paratos agrees with the accusative “subject” of the indirect statement:

• discipulos / eos = accusative plural masculine
  So the predicate adjective must match: paratos (acc. pl. masc.).

Why does the second clause use eos instead of repeating discipulos?

Latin often avoids repeating a noun by using a pronoun. Here eos simply refers back to discipulos.
You could also say magistra dicit discipulos paratos esse, but eos is smoother and avoids repetition.

Could Latin use quod or ut instead of an accusative-and-infinitive (“I’m not sure that…” / “she says that…” )?

Sometimes, especially in later Latin, you can find quod clauses. But in Classical-style Latin, after verbs/expressions of saying, thinking, perceiving, and often certus sum, the normal construction is accusative + infinitive. That’s why you see discipulos/eos … esse rather than a quod clause.

Why is non placed before sum?

That is the most common placement for a simple negation in Latin: non + verb.
It negates the whole idea of “I am certain,” i.e., “I am not certain …”

Why is there no word for that?

Latin usually doesn’t need a separate word for that when it uses the indirect statement construction. The combination accusative + infinitive already signals “that …” in English terms.

Does word order matter here—could paratos esse come earlier?

Latin word order is flexible, but patterns are common. In indirect statements, the infinitive (esse) often comes at the end of its clause, and the predicate adjective (paratos) often stands right before it.
You could rearrange for emphasis (e.g., Non sum certus paratos esse discipulos), but the given order is very typical and easy to read.