Die App, mit der ich meine Termine plane, erinnert mich auch an die Sprachprüfung nächste Woche.

Because mit always takes the dative case in German.

• The noun is die App in the nominative.
• In the dative, die becomes der.

So:

• die App = nominative
• mit der App = dative

In this sentence, der is part of the relative clause and stands for der App, so mit der means with which.

Der refers back to die App.

This is a relative pronoun, like which or that in English. German relative pronouns match the noun they refer to in gender and number, but their case depends on their role inside the relative clause.

Here:

• it refers to die App → feminine singular
• it comes after mit → dative

So the correct form is der.

Because this is a relative clause, and in German, relative clauses are always set off with commas.

Main clause:

• Die App ... erinnert mich auch an die Sprachprüfung nächste Woche.

Relative clause:

• mit der ich meine Termine plane

So the commas show that this extra information describes die App.

Because in a subordinate clause in German, the conjugated verb goes to the end.

The relative clause is:

• mit der ich meine Termine plane

Normal main-clause order would be something like:

• Ich plane meine Termine mit der App.

But once it becomes a relative clause, the verb moves to the end:

• mit der ich meine Termine plane

This is one of the most important word-order patterns in German.

Because meine Termine is the accusative plural here, and for this determiner, nominative plural and accusative plural look the same.

The verb planen takes a direct object:

• ich plane was? → meine Termine

Forms:

• nominative plural: meine Termine
• accusative plural: meine Termine
• dative plural: meinen Terminen

So:

• meinen Termine is incorrect
• meinen Terminen would be dative plural, which is not needed here

In this sentence, jemanden an etwas erinnern means to remind someone of something.

Pattern:

• jemanden = accusative person
• an + accusative = what they are reminded of

So here:

• mich = the person being reminded
• an die Sprachprüfung = what I am reminded of

That gives:

• Die App erinnert mich an die Sprachprüfung.
• The app reminds me of the language exam.

Because with jemanden an etwas erinnern, the person is in the accusative, not the dative.

So:

• erinnert mich = reminds me
• not erinnert mir

This is one of those verb patterns that just has to be learned with the case it uses.

Because an after erinnern takes the accusative here, and Sprachprüfung is a feminine noun.

So:

• nominative: die Sprachprüfung
• accusative: die Sprachprüfung

For feminine nouns, the definite article is die in both nominative and accusative, so the form does not change.

German often uses a bare time expression to say when something happens.

So nächste Woche means:

• next week

This is very natural German, just like English often says next week without a preposition.

You could also sometimes use a prepositional phrase in other contexts, but here nächste Woche is the normal, simple choice.

It is usually analyzed as an accusative expression of time.

German often uses the accusative to express when something happens:

• nächste Woche = next week
• diesen Montag = this Monday
• jeden Tag = every day

So even though there is no preposition, the phrase still has a grammatical case.

Auch means also or too.

Here it suggests that the app does something in addition to something else:

• it not only helps plan appointments, it also reminds me about the exam

Position matters with auch, because it often highlights what is being added. In this sentence:

• erinnert mich auch an die Sprachprüfung

the auch naturally modifies the whole reminding action.

Because German very often forms compound nouns.

• Sprache = language
• Prüfung = exam/test

Together:

• Sprachprüfung = language exam

In compounds, the last part is the main noun, so die Sprachprüfung is feminine because die Prüfung is feminine.

Because the whole phrase Die App, mit der ich meine Termine plane, counts as the first element of the main clause.

German main clauses follow the verb-second rule:

1. first element
2. conjugated verb
3. the rest

So the structure is:

• Die App, mit der ich meine Termine plane, = first element
• erinnert = verb in second position
• mich auch an die Sprachprüfung nächste Woche = rest

Even though that first element is long, it still counts as one unit before the verb.

Because German, like English, often uses the present tense for something that is true now or happens regularly, even if it refers to a future event.

The idea is:

• the app is currently functioning as a reminder
• what it reminds me about is an event next week

So this is completely natural:

• Die App erinnert mich ... an die Sprachprüfung nächste Woche.

It does not mean the exam is happening now; it means the reminder is relevant now for an exam happening next week.