Mastering Metrics - Dr. Annette M. Parrott printable pdf download

S C I E N C E

sampler

Mastering metrics

By the time students reach a middle school science course,

How much does your average 2.5 gram penny weigh?

they are expected to make measurements using the metric

47 apothecaries’ drams

(12 grams)

system. However, most are not practiced in its use, as their

b.* 39 grains

(2.5 grams)

experience in metrics is often limited to one unit they

20 scruples

(15 grams)

were taught in elementary school. This lack of knowledge

1 pennyweight

(1.5 grams)

is not wholly the fault of formal education. Although the

metric system has been around since the 1600s and its use

At what temperature does water freeze?

was made legal in the United States in 1866, most U.S.

0° Fahrenheit

(–18°C)

residents are not proficient with it. It is usually necessary

b.* 492° Rankine

(0°C)

to re-teach the metric system before students can collect

32° Celsius

(32°C)

and report data in scientific terms.

100 Kelvin

(–173°C)

I introduce the metric system by giving students an

oral quiz. I give them categories for each question and

After the not-so-metric measurement quiz, it is usually apparent

then ask for volunteers. For example, the first question

to students that a vast array of measurement units are used in

might be, “Who thinks they know how tall they are?” I

the English language. To add to the confusion, I inform them

usually pick a student who is close to 6 feet tall to answer

that although their car may hold 20 gallons of gas in the United

this question. Then I ask him or her, “Which measure

States, if they drove to Canada it would only hold 16.59 Ca-

best describes the height of a person who is 6 feet tall: 1

nadian gallons. This illustrates that sometimes even the same

league, 1 fathom, 1 rod, or 1 furlong?” Students are at

unit means different things. We discuss how a U.S. short ton

first taken aback by such a line of questioning, but then

equals 2,000 pounds, a U.S. long ton equals 2,240 pounds, a

rise to the challenge and want to figure it out. Some of

nautical ton equals 100 cubic feet, and a freight ton equals 40

the questions that I pose to students are listed below,

cubic feet; so although ton can be an ambiguous term, there is

along with correct answers (denoted by asterisks) and

little ambiguity in kilometer and other metric units.

conversions are in parentheses. You could also provide

As a follow-up to the quiz, I ask students to define ton and

the questions to students on a handout and they could

provide a variety of resources for students to look in (that have

do research online or in the library to find the answers.

different definitions). When students return with their researched

answers, they have differing definitions of ton, which leads them

How tall is a 6 foot person?

to their next quest, to find the history of the ton measurement.

1 league

(15,840 feet)

Once students find out the history of the ton, they realize that

b.* 1 fathom

(6 feet)

there are several different types of tons used for different things.

1 rod

(16.5 feet)

I also ask students to investigate the history of measure-

1 furlong

(5,282 feet )

ment in general and to report on early measurement units

and tools used by ancient peoples. Students find that early

How much milk is in a gallon jug?

humans used all sorts of readily available items (including

2 pints

(1/4 gallon)

rocks, body parts, and so on) to standardize measurement.

2 quarts

(1/2 gallon)

After teaching students about the units that are used

5 pecks

(2 gallons)

in scientific measurement, I have them build the metric

d.* 32 gills

(1 gallon)

box (Figure 4). The metric box is a small paper cube that

students measure, cut, fold, and tape. Students practice

How much does a quarter-pound burger weigh before

measuring and recording lengths and then represent those

cooking?

collective lengths graphically and numerically. The metric

a.* 1,750 grains

(1/4 lb)

box is an exercise in following directions, making metric

128 drams

(1/2 lb)

measurements, and collecting and displaying data.

8 ounces

(1/2 lb)

Annette M. Parrott () is a science educator

1 hundredweight

(100 lbs)

at Lakeside High School in Atlanta, Georgia.

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Mastering Metrics - Dr. Annette M. Parrott

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