There is sometimes confusion over which to use of these verb forms: the Present Simple or Present Continuous vs Present Perfect.

The cat is here.
vs
The cat has been here.

Simon is writing.
vs
Simon has been writing.

Generally speaking we would use the present simple or present continuous to talk about something which is happening as we speak. In the examples above I can see the cat on the chair and maybe I can hear Simon banging away on the keyboard in the other room.

However the perfect is used to talk about something which happened in the past but still has a great effect now. In the examples above I might not be able to see the cat but I can see cat hairs on the chair; I might not be able to hear Simon working but I can see a large pile of papers on the table which he has just printed out.

In your TEFL class you need to make the distinction that the present perfect is only used when the action or situation is finished, but the after-effects can still be seen or felt.

The next question, of course, is the difference between the simple past and the present perfect!

The cat was here.
vs
The cat has been here.

For more on this, see Present Perfect vs Past.

Useful Links

Present Simple‏‎ in English Grammar – formation, usage, examples

Present Continuous‏‎ in English Grammar – formation, usage, examples

Present Perfect Simple‏‎ in English Grammar – formation, usage, examples

Present Perfect Continuous‏‎ in English Grammar – formation, usage, examples

Present Perfect Continuous vs Simple?‏‎ – which is best to use?