Learn Spanish (Spain): Los niños deben dormir mucho.

In Spanish, when you talk about a noun in a general sense (like all children), you must use the definite article (el, la, los, or las). English usually drops the word "the" for general statements, but Spanish requires it.

Why is "deben" translated here as "should" instead of "must"?

The verb deber can mean either "must" (an obligation) or "should" (a strong recommendation) depending on the context. While Spanish has a softer conditional form for "should" that you will learn later, using the present tense deben is a very common way to express strong, practical advice.

Why is "dormir" not conjugated?

When you use a verb of obligation or ability like deber right next to another verb, only the first verb is conjugated to match the subject (los niños deben). The action they need to do always stays in its full dictionary form, known as the infinitive (dormir).

Since "niños" is plural, why is the word at the end "mucho" and not "muchos"?

In this sentence, mucho is an adverb describing the verb dormir (it tells us how much they sleep). Adverbs never change their ending to match gender or number. If it were describing the noun instead (like "many children"), it would be an adjective and change to match it (muchos niños).