Sine of the Times - Thoughts on Math Education

On the NCTM discussion site myNCTM, there’s currently an extended discussion about “Division and multiplication of fractions.” As the discussion has continued, I’ve grown concerned with what I see as a fundamental problem with the way we often introduce...

We created the Web Sketchpad game below (and here)  as part of our Dynamic Number project. It challenges elementary-age students to uncover the value of a secret number by collecting and analyzing clues that narrow its range of possible values. The game...

In his 1947 book, One, Two, Three…Infinity, physicist George Gamow poses a pirate treasure problem that has since become a classic. Below is my reworded statement of the puzzle.
Among a pirate’s belongings you find the following note:
The island where I buried my treasure contains a single palm tree. Find the tree. From the palm tree, walk directly to the eagle-shaped rock. Count your paces as you walk. Turn a quarter-circle to the right, and walk the same number of paces. When you...

Below are two maps of the United Sates, with the smaller map a 50 -percent scaled copy of the original. The edges of the two maps are parallel. Imagine that the maps are printed out, with one resting on top of the other.
Believe it or not, you can stick a pin straight through both maps so that the pin simultaneously pierces the identical geographical location on each one! How can you find this location?...