You better give examples of sentences in the active voice and how to turn them into passive voice.
The first example you gave is an active one, but is not a good example because it doesn't have any object to serve as the subject of the passive voice .
You better say instead:
" I need you to clean the room every day."
Then form the passive voice :
" You are needed to clean the room every day.
As for the second example Eliot gave you a good example of a sentence in the active voice
"We need 3 more men to do the work."
Then your sentence will be its passive voice version:
"3 more men are needed to do the work."
This way you are drawing a comparison between the 2 voices and showing the students how to form a sentence in the passive voice.
You have to point out that the object of the active voice becomes the subject of the sentence in the passive voice.