A good problem for learners to chew over.This problem is totally solvable but takes some real thinking. Write (or print) it out and let the brainstorming begin.
The radiation problem
You are a doctor faced with a patient who has a malignant tumor in his stomach. It is impossible to operate on the patient, but unless the tumor is destroyed the patient will die. There is a kind of ray that can be used to kill the tumor. If the rays reach the tumor in sufficient intensity the tumor will be destroyed. At lower intensities the rays are harmless to healthy tissue, but they will not harm the tumor either. What type of procedure might be used to destroy the tumor with the rays without destroying healthy tissue?
Keep in mind that you are trying to destroy something inside the body without destroying healthy tissue on the way in.
Damon's class friendly version
A second question of the same type that I developed (while thinking about avoiding the whole tumor thing) makes the whole thing easier I think. Here is the same problem but couched in friendlier terms.
First, check these out.
These are small glass blocks with beautiful designs embedded within them. If you haven't seen them then drop on by your local tourist shop - they are everywhere. They are also really amazing, particularly when you begin to question HOW they were made.
I handed out several to my class, and then posed the question - how were these made?
Once they solved it, I handed out the top problem, and they totally solved it in five minutes.
So, what's the answer?