The International System of Units
The International System of Units (SI), or the metric system, is a collection of standard units for all types of measurements used worldwide. The United States is one of only three countries that does not use the metric system on a national level. All countries, the United States included, use SI units for scientific purposes. It is important that scientists have a standardized system of measurement in order to share information. When scientists share information, they can collaborate, support each other’s work, and even catch mistakes. Scientists often make measurements of length, width, temperature, area, mass, volume, and density.
Basic Units of Measurement
You may be used to measuring length in inches, feet, and miles, but how does measuring length change in the International System of Units (SI)? Note that the metric system is based on units of ten, which makes it much easier to understand and convert between bases. Each unit is ten times larger or smaller than the next unit. View this interactivity to learn the common SI units of measurement and the abbreviations for each. Click the player button to begin.
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Prefixes
Prefixes are added to the base units to represent a larger or smaller quantity. The table below shows the major prefixes used in the SI system. Based on the prefixes, a millimeter would represent 1/1000th of a meter, while a kilometer would equal 1000 meters. The metric system may seem confusing at first, but it is actually very easy to use because it is based on the number 10. For example, there are 10 millimeters in 1 centimeter, 100 centimeters in 1 meter, and 1000 meters in 1 kilometer.
Prefix | Symbol | Meaning | Examples |
kilo- |
k | 1000 times the base unit | 0.001 kilometer 0.001 kiloliter 0.001 kilogram |
hecto- |
h | 100 times the base unit | 0.01 hectometer 0.01 hectoliter 0.01 hectogram |
deka- |
da | 10 times the base unit | 0.1 dekameter 0.1 dekaliter 0.1 dekagram |
meter liter gram |
m l g |
the base unit | 1 meter 1 liter 1 gram |
deci- |
d | 1/10 of the base unit | 10 decimeters 10 deciliters 10 decigrams |
centi- |
c | 1/100 of the base unit | 100 centimetes 100 centiliters 100 centigrams |
milli- |
m | 1/1000 of the base unit | 1000 millimeters 1000 milliliters 1000 milligrams |
Are you still not sure about the SI system? Converting numbers between units only involves moving the decimal place. Look at the chart above. The smallest unit shown has the prefix milli- and the largest unit shown has the prefix is kilo-. To convert between units, you simply need to move the decimal point. If you are converting to a smaller unit of measurement, move the decimal to the right one space for each prefix. If you are converting to a larger unit of measurement, move the decimal to the left one space for each prefix. View the examples below.
Example 1:
If you wanted to convert 6000.0 meters to kilometers, you would have to move the decimal point over three places to the left. If you have converted this correctly, you will find that there are 6.0 kilometers found in 6000.0 meters.
Example 2:
How many centigrams exist in 3.0 grams of salt? Hint: This time you have to move the decimal point to the right. If you have converted this correctly, you will find that there are 300.0 centigrams in 3.0 grams of salt.
Measurement of Mass and Volume
What are mass and volume, and how do you calculate each of these important quantities? These quantities are needed to calculate density and will be found throughout your study of Earth science. To learn more about mass and volume, view this presentation. Make sure to complete the practice activity provided to you during presentation. Click the player button to begin.
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Calculating Density Using Mass and Volume
In order to calculate density, you need to know how to calculate both mass and volume. View this presentation to learn more about density and the equation to calculate it. In addition, learn why the density of water causes it to behave differently from other liquids. Make sure to complete each of the practice activities in the interactivity. Click the player button to begin.
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Parts of a Graph
Graphs may look simple, but they represent a great deal of information. A graph has several important parts that help visually display the patterns in a set of data. In this interactivity, click on each of the icons to learn more about the important parts of a graph. Click the player button to begin.
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Types of Graphs
There are many different types of graphs, and each one has a different purpose. Learning how to create and interpret graphs is an important part of conducting scientific investigations in Earth science. Different types of data require different types of graphs. In this interactivity, click on each bar in the accordion to learn about each type of graph. Click the player button to begin..
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Measurement Review
Now that you have explored measurement, complete this non-graded activity to check your knowledge. In this activity, read each question, then select the appropriate answer. Click the player button to get started.