# Introduction to Measurement

Sara DeMott, Sherry Tipps and Ruth Radomski
1991 Woodrow Wilson Biology Institute

## Purpose:

To learn to measure length with a ruler; To learn about the history and procedure of measurement; To investigate the need for standards in measurement; To understand the relationship between the English and Metric systems.

## Background:

There are two types of measuring systems: English and Metric. The English system is based on arbitrary measurements set hundreds of years ago. (For extra credit, look up how these measurements were determined.) The INCH is defined as the distance between the first and second joints of the index finger. The FOOT is defined as the length of the foot. The YARD is defined as the distance from the tip of the nose to the tip of the middle finger when the arm is outstretched. You will discover during the lab how the Metric system is defined.

## Materials:

• Ruler (6 inch/30 cm), meter stick (showing both systems), paper, pencil, calculator and graph paper

## Procedure:

WORK IN GROUPS OF THREES
1. List 5 items commonly measured in each of the following: inches, feet, yards.
2. What are some disadvantages of using the original definitions of inches, feet and yards?
3. With the ruler or the meter stick, measure the length of your finger between the first and second joints of your right hand (an 'inch'), the length of your foot (a 'foot') and the distance from the tip of your nose to the end of the middle finger on your right hand (a 'yard'). Do this for each member of your group. Record your data on your paper and on the chart on the board.
4. Calculate the average length of the 'inch', 'foot' and 'yard' for the group and for the whole class. (If more than one section is doing the same lab, collect data from all sections.) Calculate the average length of the three 'units of measure' for all of the classes.
5. Compare the length of your 'inch', 'foot' and 'yard' with the group, class, and total class averages.
6. If you were buying material or chain by the yard, who would you want to measure it? Why?
7. Fill in the following table (look at your ruler to do this).
_________ inches = 1 foot
_________ feet = 1 yard
_________ inches = 1 yard
8. How does the original inch (digit length) compare with the ruler length; with the meter stick length?
9. Use the meter stick to find the number of inches in a meter.
10. Meter sticks have units called centimeters and millimeters. What does CENTI- mean and what does MILLI- mean? State another word using each of these prefixes.
11. Look at the meter stick. Which units are millimeters and which are centimeters? Which are smaller?
12. On your paper, draw a line which is 10 mm long. Just under that line draw one which is 1 cm long. How do the two lines compare?
13. How many mm are in 1 cm?
14. What does DECI- mean?
15. On your paper, draw a line which is 10 cm long and just under that line draw one which is 1 dm long. How do the two lines compare? How many cm are in 1 dm?
16. How many mm = 1 m? How many cm = 1 m?; How many dm = 1 m?
17. Look at the answers above. What is the common factor (multiple) for each of these conversion.
18. Do you think the Metric system could be called a decimal system? Explain.

Temperature, mass and volume all have English and Metric equivalent measures. Students should design experiments to show an understanding of the equivalents. Possible ideas: Examine the freezing and boiling points of water on both the Fahrenheit and Celsius temperature scales. Students should try to develop an equation which will allow them to convert temperatures from one scale to the other. They may also simply look up the conversion equation. Mass and volume are measures in ounces and pounds in the English system and in liters, millileters and grams in the Metric system. A suggestion for data gathering would be to look at labels on food items, comparing the English and Metric equivalents listed on those labels.

## Analysis:

1. Why do you think scientists and most of the world use the Metric system?
2. What is the base unit of the metric system for measuring length? temperature? volume? and mass?
3. Most bicycles are not built in the United States. What problems would you encounter if you had to repair your bicycle yourself?
4. If you were in Iceland and the Icelanders are excited because the temperature is going to be 22 degrees outside, what will you wear to the beach? Explain.
5. You need a piece a special metal weighing exactly four pounds. This metal is processed in France in gram and kilogram amounts. What problems will you encounter in getting the piece of metal weighing exactly 4 pounds.

## Teacher Notes:

For Level II: In addition to calculating the means, have students calculate the standard deviation of a small number of samples. The students should explain the significance of standard deviation and its use in population studies.

For Level III: The students should extend Level II by using the t-test and chi-squarre and relate the information. Using larger populations would make these tests more valid. Comparing data from different classes would be a way of obtaining additional information.

## Word Parts:

Have the students learn the following prefixes and use the prefixes with the terms liters, grams and meters: milli- centi- deci- deca- centa- kilo- mega-

## Objectives:

The student should be able to observe and measure the variability in the length of the forearm and the length of the foot and to test a common belief that the length of the foot is equal to the length of the forearm.

## Procedure:

1. Set up the experimental design based on the given objectives. Be sure you answer the following questions: What is the hypothesis to be tested? What units will be used to measure? Specifically how will the foot and forearm be measured? What subgroup of the human population will be measured? How many individuals will be measured to accumulate sufficient data? What other variables need to be considered? How will you record, graph, and analyze the data?
2. Conduct the experiment and record the data.
3. Graph the data.
4. Analyze the data.
5. Evaluate the hypothesis.
6. Prepare a short presentation of your experimental design and findings for class evaluation.

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