Name Date Class------------------------------------ ------------ -------------

Measurement-A Common LanguageII Why Do Scientists Use a Standard Measurement System?

/). Standard measurement allows scientists of the metric system called the International SystemU everywhere to repeat experiments. In the 1790's, of Units, or SI. Using SI as the standard systemI scientists in France developed a system of of measurement allows scientists to compare• measurement called the metric system. The data and communicate with each other about~ metric system is a system of measurement based their results.

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What Are Some SI Units of Measure?

lenoth is the meter em).For lencths smaller than a solids. To measure the volume of a liquid, use the literIn the 51system, the basic unit for measuring sides. Use cubic meters to measure the volume of

meter, the centimeter (em) and millimeter (mm) are (U, and read the level at the bottom of the meniscus,

distances. use the displacement method: immerse the obiect inused. The kilometer (km) is used for measurinq lone or curve. To measure the volume of an irreuular solid,

water and measure how much the water level rises.

an obiect. A balance is used to measure mass bv Densitv, a measure of how much mass is containedMass is a measure of the amount of matter in

comoarinc the mass of an obiect to a known mass. in a qiven volume, is expressed as a relationshipIn SI svstem, the basic unit for measurinq mass between two units. In 51,the basic unit foris the kilouram (ko). To measure smaller masses measurina densitv is kiloarams per cubicarams (a) and milliarams (me) are used. Unlike mass

an object. A scale is used to measure weioht. In addition to the Celsius scale, scientistsweight is a measure of the force of oravitv actinc on.

sometimes use another temoerature scale, calledVolume is the amount of space an obiect or the Kelvin scale. In fact, the Kelvin (K) is thesubstance takes up. In 51,the basic unit for official 51unit for temperature. A thermometer is

meter is equal to the volume of a cube with 1-meter 51unit used to measure time.measurino volume is the cubic meter (m3).A cubic" used to measure temperature. The second Is) is the

On a separate sheet of paper, tell why scientists in different countries can easily comparethe amount of matter in similar objects in their countries.

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Mathematics and Science

01What Math Skills Do Scientists Use?

,}; Math skills that scientists use to collect data of measurements are to each other. A reliableinclude estimation, accuracy and precision, measurement is both accurate and precise.and siqnificant fiuures. An estimate is an

~pproximation of a number based on reasonableI 'assumptions, It is not a guess. Scientists often;Significant figures communicate how precisemeasurements are. The significant figures in a

I II d d Ih b~ rely on estimates w en they cannot 0 tain exact measurement inc ude a ioits measure exactiv. >

numbers. They may base an estimate on indirect plus one estimated digit. When you add or subtract.

measurements calculations models, or a sample. measurements your answer can onlv have as many, . places after the decimal as the measurement with

In science the words eccurecv and precision the fewest places after the decimal. When youhave different rneaninos. Accuracv refers to how multiply measurements the answers should on Ivdosea measurement is to the true or accepted have the same number of siqnificant fiqures as thevalue. Precision refers to how close a orouo measurement with the fewest siqnificant fiqures.

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-- What Math Tools Do Scientists Use? . . .-- ".: -:•. I"',

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Scientists use certain math tools to analyze The mean is the numerical averace of a set ofdata. These tools include calculating percent data. The median is the middle number in a set oferror; finding the mean, median, mode, data. The mode is the number that appears mostand ranee: and checkina the reasonableness often in a list of numbers. The ranee of a set of dataof data. is the difference between the qreatest value and the

-" least value in the set.Percent error calculations are awav to determinehow accurate an experimentalvalue is. A low An important part of analvzino any set of data ispercent error means.the resultvou obtained was to ask, "Are these data reasonable? Do they makeaccurate. A high per(errterror'means your result sense?" Data that do not fit with the rest of a data setwas not accurate. are anomalous data.

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On a separate sheet of paper, summarize the math skills and tools scientistsuse in their work.

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Name Date Class _

Graphs in Science

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!>.1 What Kinds of Data Do Line Graphs Display?;

.9 To help see what data mean you can use a graph. Scientists control changes in the manipulated, A graph is a "picture" of your data. One kind of variable. Then they collect data about how the

graph is a line graph. Line graphs display data responding variable changes. A line graph isthat show how one variable (the responding used when a manipulated variable is continuous,variable) changes in response to another which means there are other points betweenvariable (the manipulated variable). the tested ones.

. ... . --~ "" ..~ . ~. -..L.. "" ... - ..--.f---, Why Are Line Graphs Powerful Tools?-......; ,

A line qraph in which the data points vield a identify trends, make predictions, and recoqnizestraiaht line is a linear graph. The kind of qraph in anomalous data.which the data points do not fall alonq a straiohtline is called a nonlinear oranh. Both kinds of Graphs make it easv to see anomalous data points.line oraohs are useful. Line qraphs are powerful When a oraoh does not have any clear trends, ittools in science because they allow you to probably means that the variables are not related.

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On a separate sheet of paper, explain what line graphs show and how theyhelp scientists.

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Models as Tools in Science

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}Why Do Scientists Use Models?r

In science, a model is any representation of an object They use models as representations of things that areor process. Pictures,diagrams, computer programs, either very large, such as Earth's core, or very small,and mathematical equations are all examples such as an atom: These are physical models. Otherof scientific models. Scientists use models to models, such as mathematical equations or wordunderstand things they cannot observe directly. descriptions, are models of processes.

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'--1 What Is a System?

A system is a croup of parts that work toqether is what happens in a svstem. Outout is the materialto oerform a function or oroduce a result. All or enerov that comes out of a system. Some systemssystems have input, process, and output. Input is the also have feedback, output that chances the systemmaterial or enerov that qoes into a system. Process in some way.

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How Are Models of Systems Used? I!-

It's easyto identify the inputs and outputs of beqin to understand how enerqy moves throuqh livinqa system. It's not so easyto observe a system's thincs in an environment. However, it shows how onlyprocess. Scientists use models to understand a few of those livinq thinqs are related. So a scientisthow systems work. They also use models may build a food web to model a more completeto predict chances in a system as a result picture of the system.of feedback or input changes. However, theykeep in mind that predictions based on models are Some systemsthat scientists study are complex. Manyuncertain. parts and many variables interact in these systems.

So scientists may use a computer to keep track of alls When scientists construct a model of a system, they the variables. Becausesuch systems are difficult to

beoin with certain assumptions. These assumptions model, scientists may model only the specific parts ofallow them to make a basic model that accurately the system thev want to study. Their model may bereflects the parts of the system and their relationships. used to show the processesin the system or to makeA food chain is a qood model of a simple system to predictions .

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On a separate sheet of paper, explain how models and systems are related in science.

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Safety in the Science Laboratory;?",,",4~;"""""R"'==---~~~~====~~~-~---~~-, .=-==r=.."".="""",_. -'l

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. l Why Prepare For an Investigation?1 IV~i You must prepare before you begin a scientific chemicals. Tie back Ion a hair. Wear closed-toe

l investiaation, or lab. Good preparation helps you shoes. Wear heat-resistant cloves when handlinestay safe when doing science investigations. hot objects and plastic qloves when handlinq ~

jRead throuah any procedures carefullv. and make animals, plants, or chemicals. Handle live animals

, sure you understand all the directions. If anvthino is and plants with care. Make sure electric cords are -unclear, ask your teacher about it before you begin untangled and out of th~the lab. Lab instructions may include safety svrnbols.Safety svmbols alert you to possible sources of When you have completed a lab, be sure toaccidents in an investiqation. clean up your work area. Turn off and unpluc

any ecuioment. Dispose of any waste materialsThe most important safety rule is simple: Always properly~ Follow your teacher's instructionsfollow your teacher's instructions and the directions about proper disposal. Finallv, be sure to washexactly. When performinq a lab keep your work your hands thorouohlv after workinq in thearea clean and oraanized. Label all containers so yOU laboratorv.do not use the wronq chemical accidentally. Alsodo not rush throuah any of the steos. Move slowlv Some of vour science investiaations will beand carefullv around the room. Finallv, alwavs show done in the field, or any area outside a scienceresoect and courtesy to your teacher and classmates. laboratorv. Good preparation helps you stay safe

in the field. Alwavs tell an adult where YOU willWear safetv aoaales to Protect your eves. Wear be. Never carry out a field investiqation alone.an apron to protect your body and clothes from

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----., What Should You Do If an Accident Occurs?~

When any accident occurs no matter how minor oulcklv, Make sure you know the location and thetell vour teacher immediatelv. Then listen to Proper use of all the emeraencv eouiornent in youryour teacher's directions and carry them out laboratorv.

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On a separate sheet of paper, explain how to prepare for a scientific investigation as wellas what to do should an accident occur during one.

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