Learn Farsi: معلم بیرون مدرسه هست. - The teacher is outside the school.

hast is the independent form of "to be". We use it when talking about existence or location. Because this sentence is about where the teacher is located (outside the school), hast is the perfect choice here rather than the simple linking word ast.

How do the words for "outside" (biroon) and "school" (madreseh) connect? Is there a hidden sound?

Yes! There is a hidden "e" sound between them, known as the ezafe. When you read it out loud, you say biroon-e madreseh. This links the two words together, acting just like the word "of" in the English phrase "outside of the school".

There is no word for "the" in this sentence. How do we know it means "the teacher" and not "a teacher"?

Farsi doesn't have a direct equivalent for the word "the". A noun on its own like mo'allem is generally understood as specific ("the teacher"), especially when it's the subject at the start of the sentence. If we wanted to say "a teacher", we would usually add an "i" sound to the end (mo'allemi).

Why is hast placed at the very end of the sentence?

In Farsi, the verb or "to be" word almost always goes at the very end of the sentence. First we state the subject (mo'allem), then the location (biroon-e madreseh), and finally the verb (hast).