In an experiment, researchers exposed half the children to 2 hours of violence on television every day for a month and made sure the other half saw no violence on television at all. at the end of the month, they measured the aggressiveness in the children. the fact that the researchers ensured that some children watched violence on television and others did not is an example of:

Apopulation is a group of individuals of a single species existing together in an area. a population’s range, the area it occupies, changes over time. populations, in turn, may form a network, or metapopulation, connected by individuals that move from one group to another. within a population, the distribution of individuals can be random, uniform, or clumped, and the distribution is determined in part by the availability of resources. how might the geographic range of a species change if populations could not exchange individuals with each other? how would your answer depend on what type of metapopulation existed?

What are objects called that have value in and of themselves as well as value as a means of exchange? custom commodity money currency simple money

Which political reform gave people the power to put a proposed law on the ballot? referendum initiative direct primary recall