Is the sentence all of clues were carefully hidden by your teacher a passive or active sentence?

The sentence "All of the clues were carefully hidden by your teacher" is in the passive voice.

Here's why:

* Passive voice focuses on the action being done to the subject. In this case, the clues are being hidden.

* Active voice focuses on the doer of the action. We know the teacher hid the clues, but the sentence emphasizes the act of hiding.

To make it active voice, you would say: "Your teacher carefully hid all of the clues."