What is the primary difference between hard money and soft money?

Micah is studying child behavior in playgrounds throughout the world. he wants to see how the children react when teachers select the same child to be the first to use each piece of equipment. which approach is micah is using?

Give an example of a situation in which an individual's pursuit of economic self-interest may not benefit but instead harm the rest of society

Which groups of people most directly benefited from song innovations in the song dynasty‘s open border policy?