Active and Passive Voice
Learning the difference between active and passive voice can be tricky.
When you write a sentence with "active voice," the subject of the sentence generally performs the action.
Example: Johnny went to the store to get milk.
The Active Voice is more commonly used than the Passive Voice for non-scientific writing. Passive voice is almost always used for scientific lab reports.
With Passive voice, the subject is acted upon.
Example: Because he needed to get bread and milk, it was decided that Johnny would go to the store.
For examples of good practice in the use of the Passive Voice, you can visit the website below from the University of Wisconsin Writing Center.
writing.wisc.edu/Handbook/CCS_activevoice.html
For advice in choosing between active and passive voice, this link from Purdue University is a great resource.