formulated. These possible solutions are called hypotheses.

    In a way, any hypothesis is a leap into the unknown. It extends the scientist’s thinking beyond the known facts. The scientist plans experiments, performs calculations, and makes ob-servations to test hypotheses. For without hypotheses, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories.

    11. The word "this" in the 3rd sentence in paragraph 1 refers to ______.

    A) a good example B) an imaginary model

    C) the kinetic molecular theory D) an observed event

    12. Bricks are mentioned in the 3rd paragraph to indicate how ____.

    A) mathematicians approach science

    B) building a house is like performing experiments

    C) science is more than a collection of facts

    D) scientific experiments have led to improved technology

    13. In the last paragraph, the author refers to a hypothesis as "a leap into the unknown" in or- der to show that hypotheses ______.

    A) are sometimes ill-conceived B) can lead to dangerous results

    C) go beyond available facts D) require effort to formulate