Present Perfect and past simple----> when do we use them? Let's Simplify!

A most confusing aspect of grammar, are those two tenses we call the Past Simple and the Present Perfect- it can be quite a daunting ( make you feel worried...) task trying to come to terms with how to use them naturally.

Naturally, it takes time... So let's talk about time tonight...

Time, time, time-------> We always have to ask the question: Has the time period finished or has it not?

As a guideline: ( If you have had a grammar session with me- we know I resent the word ''rule''...) 

We use the Present Perfect for a time period that is not finished...We use the simple past for a time period that has ended/finished.

Are we talking about a finished period of time? Has it finished?

Examples:

Present Perfect:

Form: Subject+ Have/has(third person.) + third column irregular verb/participle (or regular verb+ed )

I have taught fifty six classes this week-----------> Present Perfect  (This week has not finished yet.)

Past Simple:
Form: Subject+ Second column irregular verb or regular verb+ed

I taught fifty six classes last week---------------> Past Simple (The simple past is used when the time period HAS finished.)

Are we talking about yesterdays news or is it fairly new?

Examples:

Bernadette has fallen off her chair again! ( This is new information and quite recent...)

Bernadette fell off her chair yesterday! ( This is a finished event / old news, darling! with a definite time.)

Do we include specific times in what we want to say?

Examples:

I have seen this show before! (unspecified time= we do not know when, however we know of the experience happening.)

I saw that show last week on Friday. (specified time= last week on Friday.)

We use the Present Perfect for uncompleted actions/events and to express ideas such as experience.

We most often use these indicators: For and Since:

Examples:

I have taught English as a foreign language  for two years and five months. 

( This means that I started teaching in the past and still do at present and will teach in future.)

I have taught English as a foreign language since July 2011.

We use the past simple with ''for'' when we discuss completed events:

I taught English as a second language for two years and four months ( This means I no longer do/completed event.)

For and Since:

Since=  A date/ a year / a definite point in time----> Since November, since 1988, Since the sixteenth of November

For= A duration/ a period of time ----> For two years, for a week, for a long time.