Passive but Active?

If it is passive how can  it be active, well the idea even when looks contradictory, is my  way of saying  .....We are going to learn the Passive Sentences in a dynamic way and having fun.

So here’s the definition of passive voice:

Passive Voice (n): The voice used to indicate that the grammatical subject of the verb is the recipient (not the source) of the action denoted by the verb; “‘The ball was thrown by the boy’ uses the passive voice”; “‘The ball was thrown’ is an abbreviated passive”.

The following video was made to introduce the Passive Voice

The shark doesn't have a passive role!!!

Guess Why ?...

video by Learn English with Papa Teach Me! 

Some times you use "Passive Voice"  to hide the subjet identity...lets see this case.

…Removes the focus from the person responsible for the action to the thing that was acted on. In other words, passive sentences lack an agent, which is the subject of the active verb in a sentence using active voice

A surgery was needed...

Oops , now my friends know what happened to me.