For the past few years, Scott Steketee and I have collaborated with the author team of Everyday Mathematics to integrate Web Sketchpad deeply into their curriculum.
As part of that work, I just completed a websketch that nicely mixes practice with logical reasoning. Students are challenged to find a hidden treasure on the coordinate plane by guessing its location. For each guess, students are told its taxicab distance (traveling horizontally and vertically) to the treasure. Using this information as clues, students deduce where the treasure lies.
The websketch below (and here) starts by introducing students to the way distance is measured between each guess and the treasure. The second and third pages (accessible by using the arrows in the lower-right corner) present two different views of the coordinate plane, the first showing only the first quadrant and the second showing all four quadrants.
The game is geared towards elementary-age students, but it’s suitably challenging for older students, too. Personally, I find it addicting to play!
An annotated list of all our elementary-themed blog posts is here.