Here is a reading on placebo effect along with its attendant vocabulary-building and comprehension worksheet. I don’t know if this is something high school students need to know; it is something that pops up (e.g. in an episode of Family Guy that I watched late last night) in common discourse often enough that we should at least consider its relevance to everyday life.
If you find typos in these documents, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.