Calibrated Peer Review^®

In this assignment you will

• compare and contrast measurement systems.
• recognize the variability of standard measures as a function of culture.
• identify the advantages of the SI System for science.
• write an effective persuasive essay as a method of verbal communication.

Specifically, upon completing this assignment, you will be able to

• compare units by ratio/proportion.
• understand the need to express several measurements in common units for purposes of comparison.
• convert measured values from one SI or English unit to another, and convert measured values between the two systems.

This assignment assumes that you have had prior instruction on the English system of measurement and the SI (Metric) system of measurement.

1. The Measurers

   This web site is from the Museum of the History of Science in Oxford, England. You will see how important measurement was to the medieval Flemish society by exploring the painting entitled, "The Measurers." The Flemish units of measure for weight, volume, etc., are described.

2. A Dictionary of Units

   This web site will guide you through the SI system and its correlation to the English system of measurement.

Introduction

One of the most important activities of science is measurement. Measurement is a means of quantifying properties for identification. For example, density is the relationship between the mass and volume of a pure substance. One could determine if a piece of yellow metal is gold by determining its density. Measurement allows scientists to make comparisons. Measurement also provides a means by which scientists can judge the reproducibility of experimental procedure. However, measurement is not an activity that is restricted to scientists. Every age and every culture in the world has developed a measurement system. Measurement is as old as an ancient Egyptian using a cubit unit to measure the height of a pyramid. It is as new as a programmer using a Megabyte unit to indicate the memory capacity of computer software.

Instructions for the Explorations

Follow the link named The Measurers under "Resources" to examine a Web site from the Museum of the History of Science in Oxford, England. You will see how important measurement was to the medieval Flemish society by exploring the painting entitled, "The Measurers." As you read about the various kinds of measuring devices and methods portrayed in the painting, pay particular attention to the description of the Flemish units of measure for weight, volume, etc.

Modern science uses the Système Internationale (SI) as its measurement system. The Web site, A Dictionary of Units, will guide you through the SI system and its correlation to the English system of measurement. Make sure that you are able to convert units within and between the SI and English measurement systems.

When you have completed the explorations and are able to answer all of the questions suggested in the "Guidance for Writing your Text", return to this page and continue with the writing assignment.

Something to think about: The SI measurement system was officially adopted for use in the scientific community in 1960. Prior to that most measurements intended for scientific purposes were expressed in Metric units. Given the wide variety of measuring systems in the world, why did the scientific community choose SI as their preferred measurement system?

In preparing the outline for your text consider the issues raised by the following questions:

1. Consider the English system; how are successive units of measure related? For example, look at the conversion factors for measures of length in inches, feet, and yards.
2. How are successive units of measure related in the medieval Flemish, Metric and SI systems?
3. How are new units of measure generated in each measurement system?
4. Why do national governments adopt one system of measurement, and which one is currently used by a majority of nations in the world?
5. What features of a measurement system are important for governments, business and commerce?
6. Why do scientists prefer to use only one system of measurement?
7. What features of a measurement system are important to scientists?

In writing your text pay attention to the logical flow of the ideas and transitions between sections. Your text should not be just a list of answers to the questions posed above.

Write a grammatically correct essay of the required length that defends the use of the SI measurement system in science. The essay should integrate the issues raised by the guiding questions. Be sure to compare and contrast SI to at least one other measurement system within the body of the text. Give at least three reasons for the use of the SI system in science.

Note: Formatting from word processors is NOT preserved when you copy and paste into the text box below. Click on the"Formatting Help" button to learn how to easily format your essay with subscripts and superscripts, as well as line returns and paragraphs.

ALWAYS check your formatting by using the "Preview Text" button before you submit your work. This will show you exactly how your text will appear to reviewers.

Measurement is extremely important to both everyday human interaction and to scientific research. Measurement is used to facilitate the exchange of goods and services. Countries adopt specific measurement systems to make it easier for commercial transactions to take place between communities. Measurement is the basis of much of science, where phenomena are observed, analyzed, and described. Measurements serve as evidence to support the theories that scientists propose. Thus, a scientific system of measurement must have reproducible standards, well-defined fundamental units, a range of measurements that can span from the minute to the infinite, and a logical progression between those units of measure. Of the many measurement systems developed in the world, the scientific community has adopted the Système Internationale (SI). Why is this the preferred measurement system in science?

SI is based on the Metric System. The Metric System is used by a majority of the nations in the world. There are seven fundamental units that have absolute standards based upon observable physical phenomena. Each unit can be made larger or smaller by means of prefixes that assign values based upon the decimal system. It is possible to make those units larger or smaller by using a prefix that corresponds to an appropriate power of ten. Thus, SI has reproducible standards, well-defined fundamental units, a flexible range of measurement, and a logical progression between the units of measure. For these reasons, SI is the measurement system used by the scientific community.

In the United States, an adaptation of the English measurement system is still commonly used. This system does make use of reproducible standards that are the responsibility of the federal Bureau of Weights and Measures. However, the progression between units is not predictable. For example, there are 12 inches in a foot, three feet in a yard, and 5,280 feet in a mile. The medieval Flemish system of measurement also demonstrates conversion ratio variability. The dry volume measurement of one viertel was equivalent to 4 meukens, 56 pots, 112 pintes, and 224 upers. The Flemish system had the additional disadvantage that the dry volume measurement for oats was different than that for other grains. Neither the English nor the Flemish systems of measurement meet the stringent demands for scientific measurement.

SI is the system of measurement used by science for several reasons. SI is based upon the decimal system. Its seven fundamental units is well-defined standards. New units of measure can be created by using a prefix that goes with the right decimal place. These features of SI makes it easy to make comparisons between measures taken by different people, or to express the value of very large or very small measurements, and to convert units from one to another. The English system is not as conveneint to use for science. For example, the unit of length has units of inches, feet, and miles. The conversion factors for these units don't just have diffrent decimal places. Instead, you have to memorize that there are 12 inches in a foot, three feet in a yard, and 5,280 feet in a mile. The English system is the one used in the United States. The English system is not the only measurement system that is not ideal for scientific purposes. The medieval Flemish society had a measuring system that was even more worse than the English system. The volume measurement of one viertel was equivalent to 4 meukens, 56 pots, 112 pintes, and 224 upers. The measure of one viertel was also different based on the type of grain being measured. This is not acceptable for use in science. The SI is a much better choice.

Measurement is important to society in general. Measurement systems had to be developed because business need measurement to set prices. It is important that measures have a standard so that business can take place easily in many locations. It would be very difficult to conduct business if both sides did not have agreement on measures. Scientists require high standards of measurement because reproducibility is important to the nature of science. Scientists use a measurement system to confirm experimental results and to analyze trends. The ways in which measures are used in science set very high standards for a measuring system. Measurement systems that is acceptable for use is business may not have the right range and specificity for use in science. This is why SI is the best measurement system for science.

Why is SI the preferred measurement system in science? To answer this question you have to compare the SI measurement system with at least one other measurement system.

Measurement isn't just used for science. It is important for trade among people. Governments have to decide on specific measurement systems to make it easier for trading to take place. Otherwise, people would never know how much of something they were actually buying and it would be hard to know what a good price for things would be. In science, measurement is used to assign values to use in experiments. Scientists explain things with measurements to help. But scientists need to have very precise measures. In the United States, the English measurement system is still commonly used. This system is understood by shoppers, but is not accurate enough for scientists. The conversions between units are not standardized, so you have to memorize a lot of random numbers to convert back and forth. It's not easy to do, so people usually don't convert English to Metric units and vice versa.

SI is based upon the Metric system. The Metric System is used by most other countries in the world. The fundamental units of measure are standards that are related to things in the world. Like the meter. The web site we went to says that "It is the distance light travels, in a vacuum, in 1/299792458th of a second." The other standards are the kilogram (length), second (time), ampere (elec. current), kelvin (temp), mole (substance) and candela (intensity). The fundamental units are expanded to larger and smaller units by adding a prefix. The prefixes are usually based upon Greek names. Some of them are easy to remember, like "kilo-" for 1000, but some of them are weird, like "yotta-" which means 10²⁴. The prefixes makes it possible to express measures that are much larger or much smaller than you can even imagine. In science the atom is extremely tiny and the universe is too large to comprehend. Both the atom and the universe have to be measured and described and a measurement system must be good enough to give values to express these measures.