My girlfriend teaches at a university and asked me to make her a grammar lesson on a topic of my choice. I put this powerpoint presentation together last week when I wasn't so busy (exams). I think it covers the present perfect quite well. If you use the lesson, take your time as you go through the slides, explain and provide examples. I don't think it's particularly complicated so long as your students pay attention during the presentation. Here are a list of activities as well to go with it. I quite like the idea of the yes/no lie game as I think it would get the students using the simple past and the present perfect side by side - using the present perfect for a broad/general statement and the simple past to provide more specific details.
The lesson incorporates a quite tense review at the start in order to get the students' grammar cogs turning and so practice at the end to test the students a little on what they have learned.
I think it would work in a high school but only with high level students or students who want/can be manipulated into paying attention.
Enjoy.
