TY  - BOOK
AU  - Murphy,Stuart J.
AU  - Smith,Cat Bowman
TI  - Dave's down-to-earth rock shop
AV  - QA248 .M78 2000
PY  - 2000///
CY  - New York, NY
PB  - HarperCollins
KW  - Set theory
KW  - Juvenile literature
N1  - "Classifying; Level 3."
N2  - As they consider sorting their rock collection by color, size, type, and hardness, Josh and Amy learn that the same objects can be organized in many different ways
ER  -