2.20: Appropriate Tools for Metric Measurement
Have you ever gotten a puppy? Take a look at this dilemma.
Jace has just gotten a new bulldog puppy. Jace has been wanting a bulldog puppy for a long time, and he has finally gotten his wish. Jace named his new puppy Chase and took Chase for his first appointment at the veterinarian. At the vet, the doctor weighed Chase in metric units on a scale.
Which metric unit of measurement do you think was used to record Chase's weight? Kilograms or grams?
This Concept will teach you how to think in terms of metric units. By the end of the Concept, you will know how to answer this question.
Guidance
Measurement is the system of comparing an object to a standard. As we have seen, the metric system includes units of length (meters), weight or mass (grams), and volume (liter).
When we make a measurement of length, weight, or volume, we are comparing the object against a standard (1 meter, 1 gram, 1 volume).
Tools for metric measurements provide these standards.
The metric ruler is the tool for measuring length, and width. It looks like any other kind of ruler but includes units of millimeters, centimeters, and meters.
The balance or scale is the appropriate tool for measuring weight or mass in grams. It looks something like a seesaw. With the object being measured on one side, a combination of standard weights of milligrams, centigrams, and kilograms comprise the other half. When the weight of the object being measured equals the combination of standard weights the scale balances.
A graduated cylinder measures volume. It looks like a drinking glass that has marks for volume on the side—milliliters, centiliters, and liters.
Now we can look at choosing the best tool to measure different objects. You have to think of the object and unit of measure that will be used to measure the object.
Look at this one.
Choose the appropriate tool for making the following measurements.
a) The weight of a golf ball
b) The height of a person
c) The volume of water in a chemical solution
d) The width of a table
Now, let’s think about each item and which tool would be the best choice for measuring.
a) The weight of a golf ball would be measured by the scale.
b) The height of a person would be length, so we would use a metric ruler or metric tape measure for this measurement.
c) The volume of water would be measured by a graduated cylinder.
d) The width of a table would be length, so that would be a metric ruler or metric tape.
Thinking about what is being measured whether it is length, weight or volume can help you in selecting the correct/best tool.
To find an accurate measurement, it is important to choose the right tool, but it is equally important to choose the right unit of measurement. You wouldn’t want to measure the volume of a swimming pool in milliliters—the number would be too high! The goal in choosing a unit of measure is finding the standard that most closely matches the measure of the object.
This procedure is somewhat subjective. It helps to have some real-world measurement benchmarks to act as your own personal standard. Length:
- A grain of sand is about 1 millimeter long
- A paperclip is about 1 centimeter wide
- A table could be about 1 meter tall
- A road could be about 1 kilometer long
Weight:
- A speck of dust could weigh about 1 milligram
- A paperclip weighs about 1 gram
- A kitten could weigh about 1 kilogram
Volume:
- An eyedropper holds about 1 milliliter
- A juice box holds about 25 centiliters
- A soda bottle holds about 1 liter
- A kid’s pool could hold about 1 kiloliter
Now let’s practice. Identify the best tool to measure each item.
Example A
A bag of flour
Solution: Scale
Example B
The length of a table
Solution: Ruler or tape measure
Example C
The amount of water in a pitcher
Solution: Graduated measuring cylinder
Here is the original problem once again.
Jace has just gotten a new bulldog puppy. Jace has been wanting a bulldog puppy for a long time, and he has finally gotten his wish. Jace named his new puppy Chase and took Chase for his first appointment at the veterinarian. At the vet, the doctor weighed Chase in metric units on a scale.
Which metric unit of measurement do you think was used to record Chase's weight? Kilograms or grams?
Chase is a puppy and doesn't weight a lot. Let's review the different metric units that we use for measuring weight. A milligram is for very tiny things such as a bean or a dust particle. A gram measures slightly heavier things like a paperclip or a pencil. A kilogram is used for things with definite weight, like a kitten or a dog.
The vet would have measured Chase in kilograms.
Vocabulary
Here are the vocabulary words in this Concept.
- Equivalence
- means equal.
- Metric System
- a system of measuring length, weight and volume
- Milli
- means \begin{align*}\frac{1}{1000}\end{align*}
- Centi
- means \begin{align*}\frac{1}{100}\end{align*}
- Kilo
- means 1000
- Measurement
- comparing the quality of an object against a standard based on what you are measuring.
- Metric Ruler
- the tool for measuring length
Guided Practice
Here is a problem for you to try on your own.
Imogene is buying material for a costume. She buys 3.15 meters of purple material at $4.12 a meter, 2.25 meters of yellow material at $8.63 a meter; and .5 meters of gold ribbon at $1.30 a meter. How much does she spend on her costume? (Be sure to round your prices to the nearest hundredth.)
Answer
This problem asks us to find the total Imogene spent on her costume. We know the measurements of the three materials and the cost of each type of material, so we need to multiply all three measurements by their cost and add them together.
\begin{align*}&3.15(\$4.12) + 2.25(\$8.63) + 0.5(\$1.30)\\ &\$12.98 + \$19.42 + \$0.65\end{align*}
Imogene spent $33.05 on her costumes.
Video Review
Here is a video for review.
- This is a James Sousa video on metric unit conversion.
Practice
Directions: Choose the appropriate tool for the following measurements.
1. the volume of a water balloon
2. the length of a basketball court
3. the weight of an apple
4. the volume of a milk carton
Directions: Choose the appropriate unit for the following measurements:
5. the distance between two towns
6. the weight of a peanut
7. the length of a hand
8. the volume of a raindrop
9. the weight of a person
10. the weight of a bag of sand
11. The height of a table
Directions: Solve each problem.
12. The town square has a length of 39.2 meters and a width of 17.5 meters. What is the perimeter of the square? [Remember: \begin{align*}P = 2l + 2w\end{align*}]
13. A pharmacist mixing cough syrup mixes 1,550 milliliters of syrup, 725 milliliters of cherry flavor, and 1.25 liters of water. Once mixed, what is the total volume of the cough syrup in liters?
14. A stable houses horses with the following weights. Arnaud: 331.6 kg; Josie: 331,061 g; Max: 331,612 g; Taboo: 331.61 kg. Order the horses from greatest to least weight.
15. At the farmer’s market, Josh bought 1.5 kilograms of oranges, 150 grams of grapes, and 15,000 centigrams of apples. How many grams of fruit did he buy in all?
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Here you'll learn to choose appropriate tools and units for given measurement situations.