The maya based their calender on careful observations of

Which event in the history of the americans with disabilities act is an example of a conflict between different levels and branches of government?

What was the main motivation for the early populists

Which statement is a good description of a model? a) models are a description of nature based only on one or two variables. b) models are testable ideas but they are not very to most people. c) models are a description of nature that predicts more accurately than real events. d) models are an approximiation of a real system that omits all but most essential variables in a system.