Learn Hardcore German: In der Lern-App zeigt ein grüner Fortschrittsbalken als Symbol, wie viel Wortschatz du heute schon geschafft hast. - In the learning app a green progress bar shows as a symbol how much vocabulary you have already done today.

English would usually put the subject first:
“In the learning app, a green progress bar shows …”
German just allows that initial adverbial to come first instead of the subject.

Why is it ein grüner Fortschrittsbalken and not something like einen grünen Fortschrittsbalken?

Fortschrittsbalken is masculine (der Fortschrittsbalken). Here it is the subject of the sentence, so it is in the nominative case.

Masculine nominative with ein: ein
Adjective ending in that pattern: grüner

So:

ein (indefinite article, nominative masculine)
grüner (adjective, nominative masculine after ein)
Fortschrittsbalken (noun)

If it were an object in accusative, you’d see:

einen grünen Fortschrittsbalken (accusative masculine).

Here it’s the subject, so ein grüner is correct.

Why does the adjective end in -er in grüner?

The ending -er is the regular adjective ending for:

Case: nominative
Gender: masculine
Article: ein (indefinite article)

Pattern (masculine, nominative):

ein grüner Fortschrittsbalken
kein grüner Fortschrittsbalken

With der, it would be:

der grüne Fortschrittsbalken (definite article → -e).

What exactly is Fortschrittsbalken, and how is it formed?

Fortschrittsbalken is a compound noun:

der Fortschritt = progress
der Balken = bar

In the compound, Fortschritt appears as Fortschritts- (a linking -s, similar to English “progress bar”, where “progress” modifies “bar”).

So Fortschrittsbalken literally is “progress bar” and, like all German nouns, is capitalized.

What does als Symbol do here grammatically? Could it be left out?

als Symbol is a kind of predicative complement to zeigt. Roughly:

zeigt … als Symbol, wie …
= “shows … as a symbol of how …”

It clarifies that the green progress bar functions as a symbol of your completed vocabulary.

You could leave it out:

In der Lern-App zeigt ein grüner Fortschrittsbalken, wie viel Wortschatz du heute schon geschafft hast.

This would still be correct, just slightly less explicit about the symbolic role of the bar. Another common verb for this idea is dient als Symbol (“serves as a symbol”).

Why is there a comma before wie in …, wie viel Wortschatz du heute schon geschafft hast?

Because wie viel Wortschatz du heute schon geschafft hast is a subordinate clause (a dependent clause) acting as the object of zeigt:

zeigt, wie viel Wortschatz du heute schon geschafft hast
= “shows how much vocabulary you have already managed today”

In German, all subordinate clauses are separated from the main clause with a comma. Words like wie, dass, weil, ob, etc., typically introduce such clauses.

Why is it wie viel Wortschatz and not wieviel or wie viele Wörter?

Three points:

Spelling:
Modern standard German usually writes wie viel as two words, especially when it’s about quantity in general. wieviel (one word) still appears, but wie viel is preferred.
Wortschatz vs. Wörter:
- Wortschatz = vocabulary (as a mass/collective noun)
- Wörter = individual words (countable items)
Here we’re talking about how much of your vocabulary learning you’ve done, so Wortschatz as a mass noun makes sense.
wie viel vs. wie viele:
- wie viel Wortschatz → uncountable/mass: “how much vocabulary”
- wie viele Wörter → countable: “how many words”

So you could say wie viele Wörter du heute schon gelernt hast (how many words you’ve learned), but the original focuses on your vocabulary progress in general.

Why is the verb at the end in … du heute schon geschafft hast?

Because this is a subordinate clause introduced by wie. In subordinate clauses, the conjugated verb goes to the final position.

Structure here:

du (subject)
heute (time)
schon (adverb “already”)
geschafft (past participle)
hast (conjugated auxiliary at the very end)

So the perfect tense (Perfekt) splits into:

participle (geschafft) + auxiliary (hast at the end of the clause).

In a main clause you’d say:

Du hast heute schon viel Wortschatz geschafft. (verb in 2nd position)

But in the subordinate clause:

…, wie viel Wortschatz du heute schon geschafft hast. (verb-final).

Why is geschafft used here and not gemacht or gelernt?

schaffen (in this context) means “to manage”, “to get done”, “to complete”:

Ich habe heute viel geschafft. = I got a lot done today.

So:

Wortschatz geschafft haben = to have managed/covered a certain amount of vocabulary.

Alternatives:

gelernt (from lernen) focuses specifically on learning:
wie viel Wortschatz du heute schon gelernt hast
gemacht (from machen) is more general “did/made” and sounds a bit off for vocabulary here.

geschafft fits well with the idea of progress/amount completed rather than just the act of learning.

What’s the nuance of heute schon here? Could it be schon heute?

heute schon usually means “already today / so far today” and emphasizes what you’ve done up to now in the course of today.
- Wie viel hast du heute schon geschafft? = How much have you already done today?
schon heute can mean more like “already today (so early)”, often contrasting with a later expected time:
- Schon heute kannst du große Fortschritte machen.
  = Already today you can make big progress (earlier than you might think).

In this sentence, heute schon is correct because the idea is progress so far today.

Why is it du and not dir or dich? And what about Sie?

du is the nominative (subject) form of the informal second-person singular:

du (subject)
dich (accusative object)
dir (dative object)

Here du is the subject of hast:

du … hast = you have

So nominative du is required; dir or dich would be wrong in this position.

Regarding formality:

du = informal “you” (to friends, kids, many apps and games use this)
Sie = formal “you”

A more formal version could be:

… wie viel Wortschatz Sie heute schon geschafft haben.

Could we say zeigt dir (shows you) in this sentence?

Yes, that’s possible and would add an explicit indirect object:

In der Lern-App zeigt dir ein grüner Fortschrittsbalken als Symbol, wie viel Wortschatz du heute schon geschafft hast.

Here:

dir = dative object (“to you”)

The meaning would be:
“In the learning app, a green progress bar shows you, as a symbol, how much vocabulary…”

In the original, dir is simply implied; many German sentences omit this when it’s obvious from context.

Why is Lern-App written with a hyphen, and what gender does it have?

Lern-App is a compound of:

lernen / Lern- (learning)
die App (app / application)

German often uses:

solid compounds: Lernapp (less common here)
or a hyphen: Lern-App, which is clearer and more readable, especially with foreign words like App.

The grammatical gender comes from App, which is feminine:

die App → die Lern-App

That’s why we say in der Lern-App (dative feminine singular).