Volume I. THIS AND THAT    
QC indicates a Quick Challenge.  TC indicates a Tough Challenge.

Vol I. #1. Carbon-14 Dating  Middle School and higher

Vol I. #2  Horse Power  Middle School and higher

Vol I. #3  Density TC  Senior High School

Vol I. #4  Sex-linked Traits Middle Level

Vol I. #5  Rapid Growth  - QC

Vol I. #6  Calculating Cost  - QC

Vol I. #7  Construction Costs - TC - A building trades challenge

Vol I. #8  You Can't Lose Your Marbles  Middle School through High School

Vol I. #9  Air Pressure and Density  Middle School and higher

Vol I. #10  World Records - On The Moon?!?   All levels - For the fun of it

Vol I. #11  Attention Geniuses  Math Riddles, All levels

Vol I. #12  A Tough One  TC - Math riddle for High School

Vol II. HEROES AND VILLAINS is in the works - stay tuned!