Heute markiere ich jedes Nomen blau und jedes Verb rot in meinem Heft.

German main clauses follow the V2 rule: the finite verb goes in the second position.

So in:

Heute markiere ich jedes Nomen blau und jedes Verb rot in meinem Heft.

the first position is taken by Heute, so the verb markiere must come next, and the subject ich comes after it.

Compare:

• Ich markiere heute ...
• Heute markiere ich ...

Both are correct, but the word in first position gets more emphasis.

Because Nomen and Verb are both neuter nouns in German:

• das Nomen
• das Verb

The determiner jeder / jede / jedes changes to match the noun’s gender, number, and case.

Here both nouns are:

• singular
• neuter
• accusative (because they are direct objects of markiere)

For neuter singular nominative/accusative, the form is jedes.

So:

• jedes Nomen
• jedes Verb

In German, all nouns are capitalized, not just names or sentence beginnings.

So:

• das Nomen
• das Verb
• das Heft

This is one of the biggest visual differences from English.

Because here blau and rot are not attributive adjectives placed directly before a noun. They are describing the result of the marking.

Think of it like:

• mark something blue
• mark something red

In German, after verbs like markieren, color words often stay in their basic form:

• etwas blau markieren
• etwas rot markieren

No adjective ending is added here.

But if the adjective comes before a noun, then it does take an ending:

• das blaue Nomen
• das rote Verb

They function as object complements or resultative descriptions. They tell you what color the object is marked.

So:

• jedes Nomen blau markieren = to mark every noun blue
• jedes Verb rot markieren = to mark every verb red

This is similar to English patterns like:

• paint the door red
• color the sky blue
• mark the mistakes green

Because in can take either accusative or dative, depending on meaning:

• accusative for movement toward something
• dative for location in something

Here the meaning is location: the marking happens in the notebook, not into the notebook.

So German uses dative:

• in meinem Heft

Compare:

• Ich schreibe in meinem Heft. = I write in my notebook.
• Ich lege das Blatt in mein Heft. = I put the sheet into my notebook.

Because Heft is neuter: das Heft.

After in with a location meaning, we need dative, and the possessive determiner mein- changes accordingly.

For neuter singular dative, the form is meinem.

So:

• nominative: mein Heft
• accusative: mein Heft
• dative: meinem Heft

That is why the sentence has in meinem Heft.

Because each noun phrase needs its own determiner here.

The sentence is really:

• jedes Nomen blau
• und jedes Verb rot

Repeating jedes makes the structure clear and balanced.

If you removed it, the sentence would sound incomplete or wrong:

• Heute markiere ich jedes Nomen blau und Verb rot ... ✘

You need:

• jedes Nomen ... und jedes Verb ... ✔

Yes, but the meaning shifts slightly.

• jedes Nomen / jedes Verb = each noun / each verb
• alle Nomen / alle Verben = all nouns / all verbs

In many real contexts, both are possible and often similar in meaning. But jedes focuses more on items one by one, while alle refers more to the whole group.

Also note that with alle, the nouns become plural:

• alle Nomen
• alle Verben

Yes. markieren is a regular verb.

Its present tense is:

• ich markiere
• du markierst
• er/sie/es markiert
• wir markieren
• ihr markiert
• sie/Sie markieren

So markiere is just the normal ich form.

Yes. German word order is flexible, as long as the verb rules are respected.

You could also say:

• Heute markiere ich in meinem Heft jedes Nomen blau und jedes Verb rot.
• In meinem Heft markiere ich heute jedes Nomen blau und jedes Verb rot.

These versions are grammatical, but they shift the emphasis slightly.

The original sentence sounds natural and keeps the place phrase near the end.

It is a time adverb meaning today, and it sets the time frame for the whole sentence.

By placing Heute first, the speaker emphasizes today:

• Heute markiere ich ... = Today, I’m marking ...
• Ich markiere heute ... = I mark ... today

Both are correct, but the first version highlights the time more strongly.

German often uses jed- words to express each/every in a very natural way, even where English might more often prefer a plural phrase.

So:

• jedes Nomen = every noun
• jedes Verb = every verb

This is completely normal German. It does not sound strange or overly formal here.

English and German do not always choose singular vs. plural in exactly the same situations, so it is best to learn the German phrase as its own pattern.