Magistra discipulos monet ut lente ascendant et ne in scalis currant.

Because moneo takes a direct object: magistra discipulos monet = the teacher warns/advises the students.

So the basic structure is:

• magistra = the teacher, nominative subject
• discipulos = the students, accusative direct object
• monet = warns/advises

After that, Latin adds the content of the warning with ut and the subjunctive.

This is an indirect command (sometimes also called a substantive clause of purpose after verbs of advising, warning, persuading, and so on).

After verbs like moneo, impero, persuadeo, rogo, Latin often uses:

• ut
  • subjunctive for a positive command
• ne
  • subjunctive for a negative command

So here:

• monet ut lente ascendant = she warns/advises them to go up slowly
• et ne in scalis currant = and not to run on the stairs

They are subjunctive because they are inside an indirect command after monet.

In English, we often use to + infinitive:

• She warns the students to go up slowly and not to run on the stairs.

Latin usually does not use an infinitive here. Instead, it uses:

• ut
  • subjunctive
• ne
  • subjunctive

So ascendant and currant are present subjunctive forms, not ordinary present indicative forms.

Because Latin distinguishes clearly between positive and negative indirect commands:

• ut = that / to
• ne = that not / not to

So:

• ut lente ascendant = to go up slowly
• ne in scalis currant = not to run on the stairs

This is very common in Latin. English often keeps the same structure and just adds not, but Latin changes ut to ne.

Because the sentence has two coordinated instructions:

1. ut lente ascendant = to go up slowly
2. ne in scalis currant = and not to run on the stairs

The et simply links them: and.

So the sense is:

• she warns the students to go up slowly and not to run on the stairs

Because lente is an adverb, meaning slowly.

It describes how they should go up:

• ascendant = they should go up
• lente = slowly

An adjective would describe a noun, but here Latin needs an adverb to describe the action.

Because in with the ablative often means in or on a place.

Here in scalis means something like:

• on the stairs
• on the staircase

So:

• in
  • ablative = location
• in
  • accusative = motion into

Since the idea is running on the stairs, not running into the stairs, the ablative is used.

Latin often uses scalae, scalarum in the plural to mean stairs or staircase, much like English often says stairs rather than a stair.

So in scalis naturally means:

• on the stairs
• on the staircase

This is just the normal idiom.

The subject is understood to be discipulos in sense, even though discipulos itself is accusative because it depends on monet.

In English, we would say:

• The teacher warns the students that they should go up slowly and not run on the stairs.

So the students are the people being told what to do.

This is normal in Latin indirect command: the person ordered or advised appears with the main verb, and the subordinate clause gives what that person is to do.

Because they refer to the students.

The forms mean:

• ascendant = they should go up
• currant = they should run

Since discipulos is plural, the verbs in the subordinate clause are also plural.

Yes. Moneo can mean several related things, depending on context:

• warn
• advise
• remind
• instruct

In this sentence, it probably has the sense warns/advises. The exact English wording may vary, but the Latin grammar stays the same.

The word order is natural Latin, but Latin is more flexible than English.

A helpful way to see the structure is:

• Magistra discipulos monet
• ut lente ascendant
• et ne in scalis currant

Latin often puts the main statement first and then the content of the instruction afterward. English does something similar here, but Latin can move words around more freely because the endings show their roles.