Soft and Hard

How do we use soft materials? What is the hardest material of all? Can things change from hard to soft? Read 'Soft and Hard' to find out! Learn how some things can be made from both soft and hard materials, how air can make things soft, and how things can change from soft to hard. Each book in the 'My World of Science' series explains science that you see in the world around you and use every day.