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　　Scientific Theories

　　In science, a theory is a reasonable explanation of observed events that are related. A theory often involves an imaginary model that helps scientists picture the way an observed event could be produced. A good example of this is found in the kinetic molecular theory, in which gases are pictured as being made up of many small particles that are in constant motion.

　　A useful theory, in addition to explaining past observations, helps to predict events that have not as yet been observed. After a theory has been publicized, scientists design experiments to test the theory. If observations confirm the scientist’s predictions, the theory is supported. If observations do not confirm the predictions, the scientists must search further. There may be a fault in the experiment, or the theory may have to be revised or rejected.

　　Science involves imagination and creative thinking as well as collecting information and performing experiments. Facts by themselves are not science. As the mathematician Jules Henri Poincare said, “Science is built with facts just as a house is built with bricks, but a collection of facts cannot be called science any more than a pile of bricks can be called a house.”

　　Most scientists start an investigation by finding out what other scientists have learned about a particular problem. After known facts have been gathered, the scientist comes to the part of the investigation that requires considerable imagination. Possible solutions to the problem are 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 observations to test hypotheses. Without hypothesis, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories.

　　科学理论

　　在科学中，理论是对所观察到的相关事件的合理解释。理论通常包含一个虚构的模型，

　　这个模型帮助科学家构想所观察到的事件是如何发生的。分子运动理论便是我们能找到的一个很好的例子。

　　在这个理论中，气体被描绘成由许多不断运动的小颗粒组成。一个有用的理论，除了能够解释过去的观测，还有助于预测那些未被观测到的事件。一个理论公开

　　后，科学家们设计实验来检验这个理论。如果观察证实了科学家的预言，这个理论则得到了验证。如果观察不能证实科学家的预言，科学家就必须进一步的研究。

　　或许是实验存在错误，或许是这个理论必须被修改或抛弃。科学家除了收集信息和操作实验外还需要想象能力和创/造性思维。事实本身并不是科学。

　　正如数学家乔斯?亨利?波恩克尔所说："科学建立在事实之上，就像房子用砖砌成一样。但事实的收集不能被称作科学，就像一堆砖不能被叫作房子一样。

　　"多数科学家通过找出别的科学家在一个特定问题上的所知来开始研究。在收集了已知事实之后，科学家开始了研究中需要相当想像力的部分。他们尔后拟订

　　对这个问题的可行的解决方法。这些可行的解决方式被称为假设。在某种意义上，任何假

　　设都是向未知的跳跃。它使科学家的思维超越已知事实。科学家计划实验、计算、观测以检验假定。若没有假设，进一步的研究便缺乏目的和方向。

　　当假设被证实了，就成为理论的一部分。

　　Changing Roles of Public Education

　　One of the most important social developments that helped to make possible a shift in thinking about the role of public education was the effect of the baby boom of the 1950's and 1960's on the schools. In the 1920's, but especially in the Depression conditions of the 1930's, the United States experienced a declining birth rate --- every thousand women aged fifteen to forty-four gave birth to about 118 live children in 1920, 89.2 in 1930, 75.8 in 1936, and 80 in 1940. With the growing prosperity brought on by the Second World War and the economic boom that followed it young people married and established households earlier and began to raise larger families than had their predecessors during the Depression. Birth rates rose to 102 per thousand in 1946,106.2 in 1950, and 118 in 1955. Although economics was probably the most important determinant, it is not the only explanation for the baby boom. The increased value placed on the idea of the family also helps to explain this rise in birth rates. The baby boomers began streaming into the first grade by the mid 1940's and became a flood by 1950. The public school system suddenly found itself overtaxed. While the number of schoolchildren rose because of wartime and postwar conditions, these same conditions made the schools even less prepared to cope with the food. The wartime economy meant that few new schools were built between 1940 and 1945. Moreover, during the war and in the boom times that followed, large numbers of teachers left their profession for better-paying jobs elsewhere in the economy.

　　Therefore in the 1950’s and 1960’s, the baby boom hit an antiquated and inadequate school system. Consequently, the “ custodial rhetoric” of the 1930’s and early 1940’s no longer made sense that is, keeping youths aged sixteen and older out of the labor market by keeping them in school could no longer be a high priority for an institution unable to find space and staff to teach younger children aged five to sixteen. With the baby boom, the focus of educators and of laymen interested in education inevitably turned toward the lower grades and back to basic academic skills and discipline. The system no longer had much interest in offering nontraditional, new, and extra services to older youths.

　　公共教育的角色变化一项重要的、有可能促使人们对公共教育的角色的看法发生转变的社会发展是本世纪五

　　六十年代的生育高峰对学校的影响。在20年代，尤其是在30年代后的大萧条中，美国经历了一次出生率的下降--1920年每千名年龄在15

　　岁至45岁的妇女生下大约118个存活婴儿，

　　1930年89.2个，1936年75.8个，1940年80个。随着二战带来的持续繁荣以及随之而来

　　的经济增长，年轻人比大萧条中的同龄人更早地结婚成家，而且比前辈养育更大的家庭。

　　1946年出生率上升到102%，1950年达106%，1955年达118%。对于生育高峰，经济有可

　　能是最重要的决定因素，但它并不是唯一的解释。不断受到重视的家庭观念也有助于解释出生率的上升。到40

　　年代中期为止，这些生育高峰出生的孩子们开始源源不断地进入小学一年级。到了1950年，就形成了一股洪流。公共教育系统突然感到不堪重负了。

　　由于战时和战后的状况，使得学龄儿童人数增加，这些状况使得学校面对这股洪流更加措手不及。战时经济意味着在1940年到1950

　　年间几乎没有建立新学校。而且，在战时和随后的经济增长时期，大量的教师离开岗位去别处从事报酬更为优厚的工作。因此，在五六十年代，

　　生育高峰冲击着陈旧而不完备的学校体系。这样一来，30年代以及40年代早期，"监护理论"就不再有意义了。也就是说，通过使16

　　岁以上的年轻人留在学校不进入劳动力市场的做法再也不是教育机构的优先考虑了。因为教育机构不再能找到场地和教师来教育那些更小的5-16

　　岁的孩子。随着生育高峰，教育者和圈外人士对教育的兴趣和焦点，不可避免地转向了更低的年级和基础的学术技能和学科上。

　　这个系统不再有浓厚的兴趣给较年长的年轻人提供非传统的新式的和额外的服务。