Learn about how simple machines enable practically everything around us to work.This series takes readers (Ages 8-12) on a historical journey, examining how people coped in the past and how they developed ingenious ways to make life safer and less unpleasant. Each book...
Learn about how simple machines enable practically everything around us to work.This series takes readers (Ages 8-12) on a historical journey, examining how people coped in the past and how they developed ingenious ways to make life safer and less unpleasant. Each book...