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A. Displacing the Earth from the Center of the Universe
By the end of 12th grade, students should know that:
- People perceive that the earth is large and stationary and that all other objects in the sky orbit around it.
- Ptolemy, an Egyptian astronomer living in the second century A.D., devised a powerful mathematical model of the universe based on constant motion in perfect circles, and circles on circles.
- In the 16th century, a Polish astronomer named Copernicus suggested that all those same motions could be explained by imagining that the earth was turning around once a day and orbiting around the sun once a year.
- Johannes Kepler, a German astronomer who lived at about the same time as Galileo, showed mathematically that Copernicus' idea of a sun-centered system worked well if uniform circular motion was replaced with uneven (but predictable) motion along off-center ellipses.
- Using the newly invented telescope to study the sky, Galileo made many discoveries that supported the ideas of Copernicus.
- Writing in Italian rather than in Latin (the language of scholars at the time), Galileo presented arguments for and against the two main views of the universe in a way that favored the newer view.
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B. Uniting the Heavens and Earth
By the end of 12th grade, students should know that:
- Isaac Newton created a unified view of force and motion in which motion everywhere in the universe can be explained by the same few rules.
- Newton's system was based on the concepts of mass, force, and acceleration, his three laws of motion relating them, and a physical law stating that the force of gravity between any two objects in the universe depends only upon their masses and the distance between them.
- The Newtonian model made it possible to account for such diverse phenomena as tides, the orbits of planets and moons, the motion of falling objects, and the earth's equatorial bulge.
- For several centuries, Newton's science was accepted without major changes because it explained so many different phenomena, could be used to predict many physical events (such as the appearance of Halley's comet), was mathematically sound, and had many practical applications.
- Although overtaken in the 20th century by Einstein's relativity theory, Newton's ideas persist and are widely used.
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D. Extending Time
By the end of 12th grade, students should know that:
- Scientific evidence implies that some rock near the earth's surface is several billion years old.
- The idea that the earth might be vastly older than most people believed made little headway in science until the publication of Principles of Geology by an English scientist, Charles Lyell, early in the 19th century.
- In formulating and presenting his theory of biological evolution, Charles Darwin adopted Lyell's belief about the age of the earth and his style of buttressing his argument with vast amounts of evidence.
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E. Moving the Continents
By the end of 12th grade, students should know that:
- The idea of continental drift was suggested by the matching shapes of the Atlantic coasts of Africa and South America, but rejected for lack of other evidence.
- Early in the 20th century, Alfred Wegener, a German scientist, reintroduced the idea of moving continents, adding such evidence as the underwater shapes of the continents, the similarity of life forms and land forms in corresponding parts of Africa and South America, and the increasing separation of Greenland and Europe.
- The theory of plate tectonics was finally accepted by the scientific community in the 1960s, when further evidence had accumulated in support of it.
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F. Understanding Fire
By the end of 12th grade, students should know that:
- Lavoisier invented a whole new field of science based on a theory of materials, physical laws, and quantitative methods, with the conservation of matter at its core.
- Lavoisier's system for naming substances and describing their reactions contributed to the rapid growth of chemistry by enabling scientists everywhere to share their findings about chemical reactions with one another without ambiguity.
- John Dalton's modernization of the ancient Greek ideas of element, atom, compound, and molecule strengthened the new chemistry by providing a physical explanation for reactions that could be expressed in quantitative terms.
- While the basic ideas of Lavoisier and Dalton have survived, the advancement of chemistry since their time now makes possible an explanation of the bonding that takes place between atoms during chemical reactions in terms of the inner workings of atoms.
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G. Splitting the Atom
By the end of 12th grade, students should know that:
- The Curies made radium available to researchers all over the world, increasing the study of radioactivity and leading to the realization that one kind of atom may change into another kind, and so must be made up of smaller parts.
- Ernest Rutherford of New Zealand and his colleagues discovered that the heavy radio active element uranium spontaneously splits itself into a slightly lighter nucleus and a very light helium nucleus.
- Later, Austrian and German scientists showed that when uranium is struck by neutrons, it splits into two nearly equal parts plus one or two extra neutrons.
- A massive effort went into developing the technology for the two nuclear fission bombs used on Japan in World War II, nuclear fusion weapons that followed, and reactors for the controlled conversion of nuclear energy into electric energy.
- Radioactivity has many uses other than generating energy, including in medicine, industry, and scientific research in many different fields.
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H. Explaining the Diversity of Life
By the end of 12th grade, students should know that:
- The scientific problem that led to the theory of natural selection was how to explain similarities within the great diversity of existing and fossil organisms.
- Prior to Charles Darwin, the most widespread belief was that all known species were created at the same time and remained unchanged throughout history.
- Darwin argued that only biologically inherited characteristics could be passed on to offspring.
- The quick success of Darwin's book Origin of Species, published in the mid-1800s, came from the clear and understandable argument it made, including the comparison of natural selection to the selective breeding of animals in wide use at the time, and from the massive array of biological and fossil evidence it assembled to support the argument.
- After the publication of Origin of Species, biological evolution was supported by the rediscovery of the genetics experiments of an Austrian monk, Gregor Mendel, by the identification of genes and how they are sorted in reproduction, and by the discovery that the genetic code found in DNA is the same for almost all organisms.
- By the 20th century, most scientists had accepted Darwin's basic idea.
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I. Historical Perspectives
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There are no benchmarks for this subsection at this grade level.
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J. Harnessing Power
By the end of 12th grade, students should know that:
- The Industrial Revolution happened first in Great Britain because that country made practical use of science, had access by sea to world resources and markets, and had an excess of farm workers willing to become factory workers.
- The Industrial Revolution increased the productivity of each worker but it also increased child labor and unhealthy working conditions, and it gradually destroyed the craft tradition.
- The Industrial Revolution is still underway as electric, electronic, and computer technologies change patterns of work and bring with them economic and social consequences.
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