Here's a math-flavored puzzle I found on Andrej Cherkaev's website that I like to give to my undergraduate math students. I've paraphrased it to try to make it clearer:
A monk was instructed by his teacher to meditate for exactly forty-five minutes. But the monk didn't have a watch or a clock to use to time himself. At realizing the monk's problem, his instructor handed the monk two incense sticks that each take exactly one hour to burn. The incense sticks however are not identical, and they each burn at a non-uniform rate, since after all they are hand-made. Using these incense sticks and some matches, how can the monk arrange for exactly forty-five minutes of meditation?
I'm still not happy with the way this is worded though. Some of my students get stuck on superficial details and stuff like these
(The major issue) Many of my students don't know what I mean by the sticks not burning at a non-uniform rate. I feel like it detracts from the flow of the statement of the puzzle to have to stop and explain what that means (although they should really know that ... ), and honestly the phrase "non-uniform rate" doesn't feel right in the statement anyways.
Some students don't know what an incense stick is, which is frankly pretty important (hint: this puzzle wouldn't work with candles).
There are some complaints along the lines of, "how can the monk even notice the incense sticks are done burning if he's busy meditating?"
Some students focus too much on the matches (hint: they're only there to light the incense). I think that if I don't need to mention the matches though (if a student knows what an incense stick is, they'll know they have to burn it, right?), so this is an easy fix.
Is there another way to phrase this puzzle, like another story or situation to base this same puzzle on, that would avoid the above issues?