章节大纲

  • 常规

    全部折叠 展开全部

  • 实验实验

    What you will learn
    ::你会学到什么

    • What is an experiment
      ::什么是实验
    • Independent and dependent variables
      ::独立和依赖变量数
    • Importance of sample size and repetition 
      ::抽样规模和重复的重要性

    Various scientific experiments depicted, including lab work and field observations.

    So what exactly is an experiment?
    ::那么什么是实验?

    At first you may picture a science with microscopes and chemicals and people in white lab coats. But do all experiments have to be done in a lab? And do all scientists have to wear lab coats?
    ::一开始,你可以用显微镜和化学物质 以及白色的实验室外套里的人来描绘科学。 但是所有的实验都必须在实验室里进行吗? 所有的科学家都要穿实验室的外套吗?

    Experiments
    ::实验实验

    The Figure shows a laboratory experiment involving plants. An experiment is a special type of scientific investigation that is performed under controlled conditions, usually in a laboratory. 
    ::该图显示了涉及工厂的实验室实验,实验是一种特殊类型的科学调查,在受控制条件下进行,通常在实验室进行。

    A series of transparent containers with various plants growing in water.
    A laboratory experiment studying plant growth. What might this experiment involve?

    Some experiments can be very simple, but even the simplest can contribute important evidence that helps scientists better understand the natural world.   As many different types of experiments are possible, an experiment must be designed to produce data that can help confirm or reject the hypothesis .
    ::有些实验可以非常简单,但即使是最简单的实验也可以提供重要证据,帮助科学家更好地了解自然界。 由于许多不同类型的实验是可能的,必须设计一个实验来产生能够帮助确认或否定假设的数据。

    Variables
    ::变量变量变量

    An experiment generally tests how one variable is affected by another. The affected variable is called the dependent variable . In the plant experiment shown in the Figure , the dependent variable is . The variable that affects the dependent variable is called the independent variable . In the plant experiment, the independent variable could be fertilizer—some plants will get fertilizer, others will not. The scientists change the amount of the independent variable (the fertilizer) to observe the effects on the dependent variable (plant growth). An experiment needs to be run simultaneously in which no fertilizer is given to the plant. This would be known as a control experiment .  The plants that do not receive the fertilizer are the control group. An experiment must have a control group. In the control group, nothing is changed. It is not subjected to the independent variable. In any experiment, other factors that might affect the dependent variable must be controlled. In the plant experiment, what factors do you think should be controlled? ( Hint: What other factors might affect plant growth?)
    ::一个实验一般测试一个变量如何受到另一个变量的影响。受影响的变量称为从属变量。在图中显示的工厂实验中,从属变量是 。影响该从属变量的变量称为 独立变量。在工厂实验中,独立的变量可以是化肥——有些植物会得到肥料,另一些则不会。科学家改变独立变量(化肥)的数量以观察该独立变量(植物生长)对从属变量(植物生长)的影响。试验需要同时进行,其中不给该植物提供肥料。这将被称为控制实验。不接受化肥的工厂必须是控制组。一个实验必须有一个控制组。在控制组中,没有变化。它不受独立变量的制约。在任何实验中,可能影响该从属变量的其他因素必须加以控制。在工厂实验中,你认为应该控制哪些因素? (Hint:哪些其他因素会影响植物生长?)

    Comparison of control and experimental groups for a plant growth experiment with fertilizer.
    (Left): Control group; (Right): Experimental group

    Check your understanding!
    ::检查你的理解!

     

     

     

    Sample Size and Repetition
    ::抽样和重复

    The sample in an experiment or other investigation consists of the individuals or events that are studied, and the size of the sample (or sample size) directly affects the interpretation of the results. Typically, the sample is much smaller than all such individuals or events that exist in the world. Whether the results based on the sample are true in general cannot be known for certain. However, the larger the sample is, the more likely it is that the results are generally true.
    ::实验或其他调查的样本由所研究的个人或事件组成,样本的大小(或样本大小)直接影响到对结果的解释。通常,样本比世界上存在的所有这些个人或事件要小得多。根据样本得出的结果是否属实,一般无法肯定。然而,样本越大,结果就越有可能普遍属实。

    Similarly, the more times that an experiment is repeated (which is known as repetition) and the same results obtained, the more likely the results are valid. This is why scientific experiments should always be repeated.
    ::同样,重复试验(称为重复)的时间越多,获得的结果越相同,结果就越可能有效。 这就是为什么科学试验应该总是重复。

    Experimental Error
    ::实验错误

    Scientists make many measurements during experiments. Humans and equipment can make mistakes. Errors are often unavoidable. This is called experimental error. Errors may be due to the equipment being used. In this case, the numbers may be always skewed in one direction. For example, a scale may always measure one-half of an ounce high. People can also make errors. A measurement may not be made precisely. For example, a stopwatch may be stopped too soon or too late. But probably not always in the same direction. To correct for this, many measurements are taken. The measurements are then averaged. Experiments always have a margin of error associated with them. 
    ::科学家在实验期间进行许多测量。 人类和设备可以犯错误。 错误通常不可避免。 这被称为实验性错误。 错误可能由使用的设备造成。 在此情况下, 数字可能总是向一个方向倾斜。 例如, 比例表可能总是测量一盎司高的一半。 人们也可以做错误。 测量也可能不准确。 例如, 停止观察可能太快或太晚。 但可能不是总能向同一方向停止。 要纠正这一点, 则要进行许多测量。 然后平均进行测量。 实验总是有误差的间隔 。

     

     

    Super Microscopes
    ::超级显微镜

    Microscopes are arguably one of the most important tools of the biologist. They allow the visualization of smaller and smaller biological organisms and molecules. With greatly magnified powers, these instruments are becoming increasingly important in modern day research. 
    ::显微镜可以说是生物学家最重要的工具之一。 它们允许小生物生物生物和分子的可视化。 有了巨大的放大力,这些仪器在现代研究中变得越来越重要。

    A scientist in a lab coat uses a microscope, taking notes on a worksheet.
    In this experiment, a scientist is conducting research (and taking notes) while looking through a microscope.

     

     

    DID YOU KNOW?
    Zacharias and Han Jansen created the first compound in the 1590s with two lenses. The optical microscopes were developed between the 1590s and 1660s. For over 200 years, there was not much in microscopes until a German engineer, Carl Zeiss, revolutionized the quality of lenses in the 1850s. 
     

        

    Science Friday: The Lollipop Hypothesis
    ::科学星期五:棒棒糖假说

    Ever wondered how many licks it takes to reach the center of a lollipop? Mathematicians at NYU’s applied mathematics lab have designed experiments to determine this. Find out in this video by Science Friday.
    ::纽约大学应用数学实验室的数学家们设计了实验来确定这一点。 在科学周五的这段视频中,我们可以看到这一点。

     

     

     

    Summary
    ::摘要

    • An experiment is a special type of scientific investigation that is performed under controlled conditions, usually in a laboratory.
      ::实验是一种特殊类型的科学调查,在受控制条件下进行,通常在实验室进行。
    • An experiment generally tests how one variable is affected by another.
      ::实验一般测试一个变数如何受到另一个变数的影响。
    • The sample size in an experiment directly affects the interpretation of the results.
      ::试验的样本大小直接影响对结果的解释。
    • Repetition is the repeating of an experiment, validating the results.
      ::重复是重复实验 验证结果
    • Errors are always possible in human endeavors. Scientists have ways to reduce the effects of errors on their data.
      ::人类的努力总是有可能出错。 科学家有办法减少错误对其数据的影响。

    Review
    ::回顾

    1. What is an experiment?
      ::什么是实验?
    2. Compare the dependent variable to the independent variable.
      ::将独立变量与独立变量比较。
    3. Identify the independent and dependent variables in the following experiment: A scientist grew bacteria on gel in her lab. She wanted to find out if the bacteria would grow faster on gel A or gel B. She placed a few bacteria on gel A and a few on gel B. After 24 hours, she observed how many bacteria were present on each type of gel.
      ::科学家在实验室凝胶上种植细菌,她想了解这些细菌在凝胶A或凝胶B上是否增长更快。她在凝胶A和凝胶B上放置了几种细菌。24小时后,她观察了每种凝胶上有多少细菌。