Learn Hardcore German: Bitte erkläre mir das noch einmal. - Please explain that to me once again.

Bitte – please
- Literally means request, but in this position it works like English please.
erkläre – explain
- Imperative form (command/request) of erklären (to explain), addressed to du (informal you singular).
mir – to me
- Dative form of ich (I). It corresponds to me when it is an indirect object (to me / for me).
das – that / it
- Demonstrative pronoun: that (thing) which you want explained.
noch einmal – once more / again
- noch = still / yet / additionally
- einmal = one time
- Together: once more, one more time, again.

So the literal structure is: Please explain to‑me that once‑more.

Why is it erkläre and not erklärst or erklären?

Because this is an imperative (a request or command).

The du‑imperative of erklären is:
- (du) erkläre! or more colloquially (du) erklär!
erklärst is the present tense form for du:
- du erklärst = you explain / you are explaining
erklären is the infinitive (to explain) or the wir/Sie/sie form:
- wir erklären – we explain
- Sie erklären – you explain (formal)
- sie erklären – they explain

In an imperative addressing du, you use erkläre (or erklär) without a subject pronoun.

Where is the subject du? Why is it not written?

In German (like in English), the subject pronoun is usually omitted in the imperative:

English: (You) listen! – we normally drop you.
German: (Du) erklär(e) mir das noch einmal! – we normally drop du.

So the full version would be:

Du, erkläre mir das noch einmal.

But in normal speech and writing, you use just:

Erkläre mir das noch einmal.

The subject du is understood from the verb form erkläre.

Why is it mir and not mich?

Because mir is in the dative case, which is used for an indirect object (the person who receives something).

mir = dative (to me, for me)
mich = accusative (me as a direct object)

In Bitte erkläre mir das noch einmal:

das = the thing being explained → direct object → accusative
mir = the person receiving the explanation → indirect object → dative

Rough pattern:

jemandem etwas erklären – to explain something to someone
- jemandem → dative (here: mir)
- etwas → accusative (here: das)

If you said Bitte erklär mich noch einmal, that would grammatically mean Please explain me again (which is odd or wrong in most contexts).

What exactly is das here? Is it the or that or it?

Here das is a demonstrative pronoun, roughly meaning that (thing) or it:

It refers to something already known from the context:
- a rule, a situation, a concept, etc.

It is not the definite article das (as in das Haus = the house) in this sentence. It functions like:

Explain that to me again.
Explain it to me again.

In real communication, das usually points to something just mentioned or visible:

A: Die Grammatik ist kompliziert.
B: Bitte erkläre mir das noch einmal.
→ Please explain that (grammar point) to me again.

Could I use es instead of das, like Bitte erkläre mir es noch einmal?

In standard German, Bitte erkläre mir es noch einmal sounds unnatural.

More natural options are:

Bitte erklär es mir noch einmal.
Bitte erklär mir das noch einmal.

Some points:

Both das and es can translate as it in English, but:
- das often feels more pointing / demonstrative: that thing we talked about.
- es is more neutral: it.
With pronouns, German prefers a certain order:
- erklär es mir (accusative es before dative mir)
- or erklär mir das (das is a bit heavier than mir, so placing das after mir is fine).

So you would typically say:

Bitte erklär es mir noch einmal.
Bitte erklär mir das noch einmal.

but not …erkläre mir es….

What is the difference between noch einmal, nochmal, and wieder?

All three can relate to again, but there are nuances:

noch einmal
- Literally one more time.
- Polite, neutral, slightly more formal or careful.
- Very common in speech and writing.
- Bitte erklär mir das noch einmal.
  → Please explain that to me one more time / again.
nochmal
- Colloquial, shortened form of noch einmal.
- Very common in everyday speech.
- Erklär mir das nochmal.
  → Same meaning, just more casual.
wieder
- Literally again; can also mean back in some contexts.
- Often used for something repeated or starting again:
  - Er macht das wieder. – He is doing that again.
- With erklären, noch einmal/nochmal is more typical when asking politely for one more repetition:
  - Erklär mir das wieder can sound a bit off or context‑dependent; you usually say noch einmal/nochmal.

So, in this sentence, noch einmal (or nochmal) is the natural choice.

Is Bitte necessary? Where can I put it, and does the position change the politeness?

Bitte is not grammatically necessary, but it softens the request and makes it polite.

Possible positions:

At the beginning:
- Bitte erklär mir das noch einmal.
  → Very typical, politely framing the whole sentence.
After the verb / in the middle:
- Erklär mir das bitte noch einmal.
- Erklär mir das noch einmal, bitte.

All of these are polite. Differences are subtle:

Bitte erklär mir… – feels like a clearly marked polite request from the start.
Erklär mir das bitte… – sounds very natural and friendly in everyday speech.
…, bitte. – can sound like an afterthought “please”, similar to English.

Without bitte:

Erklär mir das noch einmal.
- Can be a neutral instruction or a bit direct, depending on tone and context.

How would I say this formally (when talking to someone I address as Sie)?

For the formal you (Sie), you change the verb form:

Bitte erklären Sie mir das noch einmal.

Structure:

Bitte – please
erklären – verb in Sie‑form (same as infinitive)
Sie – formal you (always capitalized)
mir – to me (dative)
das – that / it
noch einmal – again / one more time

So:

Informal (to a friend): Bitte erklär(e) mir das noch einmal.
Formal (to a stranger / superior): Bitte erklären Sie mir das noch einmal.

How would I say this to more than one person informally (plural ihr)?

With ihr (informal plural you), the imperative form of erklären is erklärt:

Bitte erklärt mir das noch einmal.

Breakdown:

Bitte – please
erklärt – imperative for ihr
mir – to me
das – that
noch einmal – again

So:

du (one person): Erklär mir das noch einmal.
ihr (several people): Erklärt mir das noch einmal.
Sie (formal, one or more people): Erklären Sie mir das noch einmal.

Is the word order fixed? Could I say Bitte erklär das mir noch einmal or Bitte erklär noch einmal mir das?

German word order is somewhat flexible, but there are preferences, especially with pronouns.

Most natural versions are:

Bitte erklär mir das noch einmal.
Bitte erklär es mir noch einmal.

General tendencies:

Pronouns usually come before full nouns and often cluster together:
- Erklär es mir.
- Erklär mir das.
With two pronouns (accusative + dative), German usually prefers:
- accusative before dative: Erklär es mir.

In your examples:

Bitte erklär das mir noch einmal.
- Understandable, but less natural. Native speakers usually prefer erklär mir das.
Bitte erklär noch einmal mir das.
- Sounds unnatural and broken; the adverbial noch einmal usually goes after the objects here:
  - Erklär mir das noch einmal.

So, use:

Bitte erklär mir das noch einmal.
Bitte erklär es mir noch einmal.

and avoid the other re‑orderings.

Why is noch einmal written as two words? Can I write nochmal instead?

Both forms exist:

noch einmal – two words, slightly more formal/neutral, always correct.
nochmal – one word, colloquial, extremely common in speech and informal writing.

In this sentence, all of these are acceptable depending on the tone:

Bitte erklär mir das noch einmal. – neutral, standard.
Bitte erklär mir das nochmal. – more casual, everyday speech.

In careful written German (e.g. formal letters, exams), noch einmal is usually preferred.