Our teacher help us. Change it to passive.

We are helped by our teacher.

OR

Help is provided us by our teacher.

We were helped by our teacher.

@Abhijeet: The first sentence  is ' we were helped by our teacher' because it is in past tense.

                 The second sentence is ' Help was provided to us by our teacher'. You forgot to write 'to' between provided and us. Again, it is past tense, not present tense.

Hemanth, the sentence in passive voice, will be 'We are helped by our teacher.'It is given that our teacher helps us, but it is not given that she stopped helping.

I'll explain with an example.

The florist sells flowers.

Passive-Flowers are sold by the florist.