Past Perfect Explanation

A very accurate explanation of when/why to use the Past Perfect:
(adapted from this web site: http://bit.ly/Wwl5gZ )

The past perfect tense is used to express what had happened before something else occurred in the past. This tense, while important, should be reserved for more advanced students as it's possible to communicate in English without mastering this tense. In fact, many native English speakers fail to use this tense on a regular basis. The past perfect is important to provide the reasons for decisions made in the past - We had invested heavily in research that's why we were able to succeed in the market ... (There are two actions in the past: 1.invest and 2.succeed. 1 came before 2 and explains why 2 happened) 

Introducing the Past Perfect
Providing Reasons for Past Actions
The past perfect is commonly used as a means of explaining past situations.

For Example: Let's talk a little bit about the last election. We all know that Barack Obama was elected (1). However, what had happened that caused the people to vote for him? Perhaps citizens had started (2) to see economic growth. Maybe they had decided (3) that Romney was untrustworthy. There are lots of explanations. (2 and 3 had happened before 1 happened, and they explain why 1 happened)


The next step in introducing the past perfect is understanding the difference between interrupted action in the past taking the past continuous and actions happening before a past action taking the past perfect. Do this by comparing and contrasting the two forms:

For Example: When you get home from work dinner is ready. Had dinner been cooked before you arrived, or was someone cooking dinner when you arrived?
Think back to a time you were interrupted. What were you doing when you were interrupted? Had anything happened before then to cause the interruption?