presenters topics institutions
May 10th
May 11th
May 12th
May 13th
May 14th
May 15th
May 16th
Brown
Cornell
Duke
Harvard
Ohio State
Stanford
Yale
acid rain
fossil fuels
global warming
nitrogen usage
solar energy
sulfur oxide
wind power


       Hint        Start Over

Get hints for a different puzzle!

How to Get Hints

A copy of your puzzle's grid is shown on the left. Copy over your current grid state from the book into the grid on the left by clicking once in a square to make an 'X' or twice to make an 'O'. Once you have your current grid state represented here, you can click the 'Hint' button below the grid. This will (1) remove any errors in your current grid state and (2) offer a suggestion as to where the next logical deduction can be made. You can request unlimited hints.

Puzzle #50

This grid will auto-populate with all the true relationships you've created on the top 7 rows on the grid.


Days Presenters Topics Institutions
May 10th
May 11th
May 12th
May 13th
May 14th
May 15th
May 16th