Sentence Structure: Passive Sentences 2

In an active sentence, the subject is carrying out the action.

for example:

The children climbed the tree. 

In this sentence, the children are doing the climbing, so it is an active sentence.

In a passive sentence, the subject receives the action.

for example:

The tree was climbed by the children.

The subject (the tree) is not doing the climbing, but being climbed, so it is a passive sentence.