Lesson A1–3



Lesson A1–3

USING SCIENTIFIC

MEASUREMENT

nois Biological Science Applications in Agriculture Lesson A1–3 • Page 1

Student Learning Objectives. Instruction in this lesson should result in students achieving the following objectives:

1 Describe the systems of measurement used in our country.

2 Determine the metric prefixes and units used for measuring length, volume,

weight, temperature, and area.

3 Understand how to convert numbers within the metric system.

4 Understand how to convert from one system of units to another system of units.

Describe the systems of measurement used in our country.

Anticipated Problem: What are the types of measurement used in our country?

I. There are two types of measurement used in our country—the English and the metric system.

A. Everyday measuring is done using a system of English units.

1. Units such as inch/foot, quart/gallon, and pound/hundred weight are English units.

2. Americans easily understand the English system of measurement because of our

familiarity with products measured in inches, gallons, and pounds.

B. In scientific research, the metric system, or International System of Units (SI), is used

for measuring length, volume, weight, and temperature.

1. SI is a universal language of measurement for scientists that allows them to share

information and be understood everywhere in the world.

2. Units of SI are easier to convert because they are related by powers of ten.

.

Illinois Biological Science Applications in Agriculture Lesson A1–3 • Page 3

Anticipated Problem: What are the metric prefixes and units used for measuring length,

volume, weight, temperature, and area?

II. Measuring can be accomplished using length, volume, weight, temperature, and area.

A. Length is the distance from one point to another. The SI unit of length is the meter. In

making measurements, it often is more convenient to report length in terms which signify

a portion or combination of meters.

B. Volume is the amount of space a substance occupies and is based on measurements of

length (i.e. length × width × height). The SI unit of volume is the cubic meter; however,

this measurement is too large for most scientific work so scientists normally use

cubic decimeters (.1 of a meter)3 to measure volume. One cubic decimeter (1 dm)3 is

equal to 1 liter (l).

C. Weight is a measure of the pull of gravity on an object. The SI unit of weight is the newton. Since the pull of gravity differs when you leave the earth and experiments are now conducted in space, scientists commonly measure the mass of an object, which is how much matter is in something. (For example, the moon’s gravity is approximately one-sixth that of the earth.) The SI unit of mass is the gram.

D. Temperature is the amount of heat in something. The SI unit for measuring temperature is degrees Kelvin. One degree Kelvin is equal to one degree Celsius which is the common unit of measurement for the metric system. The metric system of measuring

temperature also is based on 100. For example, there are 100° from the temperature at

which water freezes to the temperature at which water boils. Common temperature

measurements in Celsius are 18° Celsius—room temperature, 37° Celsius—body temperature.

E. Area is based on measurements of length (i.e. length × width). The SI unit for area is

the square meter (m2). However, when measuring plots of land for agricultural purposes,

the hectare (ha) is normally used instead of the square meter. 1 hectare = 10,000

square meters.

Understand how to convert numbers within the metric system.

Anticipated Problem: How can numbers be converted within the metric system?

III. Numbers can be converted within the metric system by moving the decimal points.

A. In order to convert numbers, move the decimal points using the prefixes in front of the

basic unit. When moving from a smaller unit to a larger unit, move the decimal point to

the left. When moving from a larger unit to a smaller unit, move the decimal point to the

right.

Example 1: If trying to move from 3 cm to _____ hm, move the decimal point four

places to the left. The answer would then be .0003 hm.

Example 2: If trying to move from 16 l to _____ ml, move the decimal point three

places to the right. The answer would then be 16,000 ml.

Example 3: If trying to move from 2.62 g to _____ kg, move the decimal point three

places to the left. The answer would then be .00262 kg.

Understand how to convert from one system of units to another system of units.

Anticipated Problem: How can numbers be converted from one system of units to another system of units?

IV. Numbers can easily be converted between the English and metric systems.

A. Dimensional analysis is a means of converting from one system of units to another.

1. The key idea is to get the final unit you want fixed in your mind and work toward

that unit.

2. The key operation is to multiply and divide units, just like numbers.

3. The key strategy is to set up multiplication or divisions to get all unwanted units to

cancel. If all unwanted units do not cancel out, you will know you have set up the

problem incorrectly.

Example 1: 15 in = _____ cm

Step 1: Realize that your outcome unit is cm.

Step 2: Structure your derived equation so that the units cancel out leaving

only the desired outcome unit. in × cm/in = cm

Step 3: Place the numbers into the derived equation using the equivalents that

you have learned. At least one volume, length, and weight equivalent should

be committed to memory. The most commonly used equivalents are 1 gallon

=3.79 liters, 1 inch=2.54cm, 1 pound=.45 kg. By knowing only one equivalent

conversion and understanding prefixes, you can do any conversion.

15 in × 2.54 cm/1 in =

Note: Place the equivalent in the equation as a proportion.

Step 4: Perform the mathematical task as indicated by the equation.

Note: In mathematics, the term “per” refers to division, as 2.54 cm per

inch. 15 in × 2.54 cm/1 in = 38.1 cm therefore, 15 in = 38.1 cm

This method works equally as well within either system, as shown in the following

two examples.

Example 2: 15 in = _____ yds

Step 1: The desired outcome unit is yd.

Step 2: Derive an equation that will yield the desired outcome unit.

in × yd/in = yd

Step 3: Put the numbers into the derived equation, placing the appropriate

equivalent in the proportion position.

15 in × 1 yd/36 in = .42 yd (rounded off to the nearest tenth)

Example 3: 15 ft = _____ cm

Step 1: The desired outcome unit is cm.

Step 2: The derived equation will have two proportions in it this time.

ft × in/ft × cm/in = ? cm

Note: The two proportions are inches to feet and centimeters to inches.

Step 3: Place the numbers and equivalents into the equation.

15ft × 12 in/1 ft × 2.54 cm/1 in. = 457.2 cm therefore, 15ft = 457.2 cm

Note: These calculations can be done extremely fast on a computer

once the derived equation has been set up.

Illinois Biological Science Applications in Agriculture Lesson A1–3 • Page 8

Example 5: A recent research report found a significant yield increase in corn when

a certain micronutrient was added at the rate of 20 kg per hectare. No gains were

noted below this rate, and toxicity levels occurred at higher rates decreasing yields.

Your fertilizer spreader is calibrated in pounds per acre. Can you make this conversion

accurately?

Step 1: The desired units are pounds and acres.

Step 2: The derived equations

kg × lb/kg = lb

Step 3: Place the numbers and equivalents in the equations.

Equation 1

20 kg × 1 lb/.45 kg = 44.4 lbs.

Equation 2

1 ha × 1 acre/.4 ha = 2.5 acres therefore, 20 kg/1 ha = 44.4 lb/1 acre

Biological Science Applications in Agriculture Lesson A1–3 • Page 10

Name ________________________________________ Test

USING SCIENTIFIC MEASUREMENT

Part One: Matching

Instructions: Match the word with the correct definition.

a. International System of Units e. Dimensional analysis

b. Length f. Volume

c. Temperature g. Weight

d. Area

_______1. Based on measurements of length (i.e. length × width)

_______2. The distance from one point to another

_______3. The amount of heat in something

_______4. In scientific research, this is used for measuring length, volume, weight, and temperature

_______5. The amount of space a substance occupies; based on measurements of length (i.e. length × width × height)

_______6. A measure of the pull of gravity on an object

_______7. Converting from one system of units to another system of units

Part Two: Fill in the Blank

Instructions: Complete the following statements.

1. On the Celsius scale, water _____________ at 100 degrees.

2. The _______________ _____________ __________ ___________, or the metric system, is used for measuring

length, volume, weight, and temperature.

3. Converting from the English system to the metric system can be accomplished using ________________

_________________.

4. The prefix _________________ means a thousand.

5. The SI unit of length is _____________________.

Illinois Biological Science Applications in Agriculture Lesson A1–3 • Page 11

Part Three: Multiple Choice

Instructions: Circle the letter of the correct answer.

_______1. The metric system makes it easier to convert units of measurement because it is based on units of:

a. 100

b. 10

c. 20

d. 1

_______2. If there are 18 kilograms of livestock feed, how many grams is that equal to?

a. .018

b. .18

c. 1800

d. 18000

_______3. One inch is equal to __________centimeters.

a. 2.54

b. 25.4

c. 1.61

d. .21

_______4. 28.3 grams is equal to __________kilograms.

a. 2.83

b. 28.3

c. .283

d. .0283

_______5. A soybean field is 15,400 feet long. Approximately how many meters long is the field?

a. 4,694 meters

b. 6,900 meters

c. 7,770 meters

d. 2,224 meters

Part Four: Short Answer

Instructions: Answer the following questions.

1. Why is the International System of Units (SI) used in research?

2. Why is it easier to convert units of measurement within the metric system?

3. Why has the United States been so slow to convert to the metric system?

Illinois Biological Science Applications in Agriculture Lesson A1–3 • Page 12

Illinois Biological Science Applications in Agriculture Lesson A1–3 • Page 30

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