Prezi about Passive Voice
You will find this prezi is very useful to teach Passive Voice. I includes some changes for the present, past and future with will because this has to be used as an introduction for intermediate students.
This prezi about passive voice, is one of my favourite. I normally use it in all my secondary classes and it is very effective.
What this prezi tries to do is to make students understand the structure of passive voice by themselves, so while they are watching it, they are also making their own passive voice sentences in their mind. It is a deductive way so they do not forget how to use it in the future.
It also has some exercises that goes from the most basic grammar (present simple), until the most difficult parts (be going to).I recommend you to take a look at this prezi before using it in your classes because you will need o ask your own questions at the beginning to make your students think.
Here you have the link to study it.