A [[stimulus]] or [[force]] causes change. For example, [[ice]] melts into [[water]]. The heating of the ice above 32 degrees Fahrenheit caused the immobile oxygen and hydrogen [[atoms]] to mobilize, changing the ice into water. | A [[stimulus]] or [[force]] causes change. For example, [[ice]] melts into [[water]]. The heating of the ice above 32 degrees Fahrenheit caused the immobile oxygen and hydrogen [[atoms]] to mobilize, changing the ice into water. |