Learn Hardcore Dutch: De lerares is streng maar ook serieus tijdens de les. - The teacher is strict but also serious during the lesson.

Dutch nouns are either common gender (de) or neuter (het). Both lerares (female teacher) and les (lesson/class) are common gender nouns, so they take de: de lerares, de les.

What’s the difference between lerares, leraar, docent, juf, and meester?

lerares: female teacher (explicitly feminine)
leraar: teacher (traditionally male; sometimes used generically)
docent: teacher/lecturer (often gender‑neutral, common in secondary/higher education)
juf: female primary school teacher (informal)
meester: male primary school teacher (informal)

If you want a neutral option, docent is safest in many contexts: De docent is streng…

Why is it is streng and not is strenge?

After a linking verb like zijn (to be), adjectives are in the base form (predicative): is streng, is serieus. You add -e only when the adjective comes before a noun (attributive), except with an indefinite neuter noun:

Predicative: De lerares is streng.
Attributive: De strenge lerares.
Indefinite neuter exception: een streng kind, but het strenge kind.

Can I just say streng en serieus instead of streng maar ook serieus? What’s the nuance?

streng en serieus = simply lists two traits (neutral).
streng maar ook serieus = adds a slight contrastive feel, as if acknowledging one trait and then adding another that might not be expected. It can sound more emphatic: “strict but also serious.”

Should there be a comma before maar?

No comma is needed here. In Dutch, you typically don’t use a comma before maar when it connects short phrases or words. Use a comma mainly when it joins two full main clauses. Your sentence is fine without a comma.

How does ook (also) work here? Where does it go?

Ook generally appears right before the element it modifies:

Modifying the adjective: streng maar ook serieus
Modifying the subject: Ook de lerares is streng.
Modifying the whole predicate: De lerares is ook streng. Position changes the focus of “also.” In your sentence, it adds “serious” as an additional trait.

Could I use niet alleen … maar ook … to emphasize both traits?

Yes:

De lerares is niet alleen streng, maar ook serieus. This construction explicitly highlights that both qualities apply.

Is streng the same as English “strict,” and when would I use strikt?

streng = strict as a personal trait (applies to people): een strenge lerares
strikt = strict/rigid when talking about rules, requirements, or procedures: strikte regels, een strikt schema For a person, use streng.

What’s the difference between serieus and ernstig?

serieus: serious in attitude or not joking; also “taking something seriously.” Example: Ze neemt haar werk serieus.
ernstig: grave/severe in tone or situation (illness, problems, accidents). Example: een ernstige fout, een ernstig ongeluk. For a teacher’s demeanor, serieus is the natural choice.

Can I say tijdens de les, in de les, or onder de les? Are they the same?

All can be used, with slight nuance/register differences:

tijdens de les = during the lesson (neutral, standard)
in de les = in class/while in lesson (colloquial and common)
onder de les = during class (very common in speech; slightly more informal/regional)
More formal: gedurende de les

Why is it de les and not een les?

tijdens de les often refers to the lesson currently happening or “in class” in a generic/habitual sense.
tijdens een les means “during a/one (particular) lesson,” focusing on any single instance rather than the general classroom setting. Both are possible; it’s about specificity/habituality.

Where else can I put tijdens de les in the sentence?

All are grammatical, with slight differences in emphasis:

De lerares is streng maar ook serieus tijdens de les. (neutral)
De lerares is tijdens de les streng maar ook serieus. (focuses earlier on the time frame)
Tijdens de les is de lerares streng maar ook serieus. (fronted time phrase; strong emphasis on “during class”) Remember the verb must stay in second position when you front an element: Tijdens de les is …

Why don’t we repeat is before the second adjective?

Dutch can coordinate adjectives under one copula. De lerares is streng maar ook serieus implicitly shares the same is. Repeating it (… is streng maar is ook serieus) is grammatical but sounds heavy and unnatural.

How would I negate parts of this sentence?

Not strict, but serious: De lerares is niet streng, maar wel serieus.
Not only strict, but also serious: De lerares is niet alleen streng, maar ook serieus. Use wel to contrast a positive after a negation.

What are the comparative and superlative forms of streng and serieus?

streng → strenger (comparative) → (het) strengst(e) (superlative)
Examples: Zij is strenger dan hij. / Zij is de strengste lerares. / Zij is het strengst.
serieus → serieuzer (comparative). For the superlative, speakers often prefer a periphrastic form: (het) meest serieus rather than the rare serieust.
Examples: Zij is serieuzer dan hij. / Zij is het meest serieus.

Any pronunciation tips for tricky parts like serieus and tijdens?

serieus: the eu is a rounded vowel like French in deux; many pronounce it roughly “say-ree-YOOS,” with the Dutch eu sound in the last syllable.
tijdens: ij sounds like the diphthong in English “eye” (but as one Dutch sound): “TAY-dens” (with short e in the second syllable).
streng: final ng is one nasal sound [ŋ], like the end of English “sing.”
lerares: stress on the last syllable: le-ra-RES.

Can I drop tijdens de les and still be correct?

Yes: De lerares is streng maar ook serieus. That states general traits. Adding tijdens de les limits the statement to her behavior in class.

How would the sentence look with adjectives before the noun?

De strenge en serieuze lerares is… (both adjectives take -e before the noun)
If you keep the time phrase: De strenge en serieuze lerares is zo tijdens de les.
Or you can flip it: Tijdens de les is de strenge en serieuze lerares…

Is there any difference between Dutch and English in using “seriously” vs “serious”?

Dutch often uses the same form serieus for both predicative adjectives and adverb‑like uses:

Adjective: Zij is serieus.
Adverb‑like complement: Zij neemt haar werk serieus. English splits these (serious vs seriously), but Dutch frequently doesn’t.