Puzzles
Puzzle of the Week
Nine Weights
On the table sit nine identical looking nuggets of gold. However, you know that one of the nine is a clever forgery. The only difference between the fake and the real nuggets is in weight: the fake gold weighs slightly less than the true gold. Unfortunately, this weight difference is not great enough to be noticed in human hands. Fortunately, you have a standard balance scale. Unfortunately, you may only use the balance scale twice. Fortunately, there is a way to find the fake gold even with these restrictions. How?
Math Puzzle Wiki
I am a big proponent of using mathematical puzzles as a teaching tool. To that end, I have started a collection of my favorite puzzles (including the one above) on what I'm calling the Math Puzzle Wiki. It is intended primarily for fellow math teachers as a resource for in class activities and extra credit problems but it might also be interesting to puzzle enthusiasts. You are welcome to add puzzle or improve ones already there.