In checkers If I see my opponent can make a jump and they don't see the jump should I tell them? What if I have a plan for after they make the jump and they don't take it. That spoils my plan.
It depends on if you are playing with mandatory capture rules or not. If you are playing with mandatory capture and they make a move instead of capturing a piece then you should tell them because they would be required to make the capture instead of another move. If you are not playing with mandatory capture then it doesn't matter but you can still tell them if you chose to.