Earth Science Textbook Skills Handbook

Making Measurements By measuring , can express their observations more precisely and communicate more Information about what they observe . Measuring in SI The standard system of measurement used by scientists around the world is known as the International System of Units . which is ated as Si ( System Unit , in ) units are easy to use because they are based on multiples of IO . unit is ten times larger than the next unit and one tenth sir of the next largest unit . The table lists the used to name the common SI units . Length To measure length . or the distance between two points , the unit of is the meter ( The distance from the to a knob is approximately one meter . Long distances . such as the distance tween two cities , are measured in kilometers ( Small lengths are measured in centimeters ( or millimeters ( Scientists use metric rulers and meter sticks to measure length . Common ( The larger lines on the metric ruler in the picture show centimeter divisions . while the smaller . unnumbered lines show divisions How many centimeters long is the shell ?

How many millimeters Common SI Prefixes he it do A to ( one hundredth ) one thousandth ) Liquid Volume To measure the volume of liquid . or the amount it takes up . you will use a unit of measure known as the liter ( One liter is the approximate volume of carton of milk . Smaller volumes are measured in milliliters ( Scientists use graduated cylinders to liquid volume . Common Conversion The graduated in the picture is marked in milliliter divisions Notice that the water in the cylinder has a surface . Yhis curved surface is called the meniscus . To measure the volume , you must read the level at the lowest point of the meniscus . What is the volume oi water in this graduated cylinder ?

Man To measure mass . or the amount of matter in an object . you will use a unit of measure known as the gum ( One gram is approximately the mass ofa paper clip . Larger are measured in kilograms ( Scientists use a balance to the mass of an object . Common Conversion I measured in kilograms . what is the mass of the potato ?

Suppose a recipe tor potato salad called for one of About how many potatoes Converting SI Units To use the 51 system , you must know how to convert between units . Converting from one unit to another involves the skill of calculating . or using mathematical operations . Converting between SI units is similar to convening between dollars and dimes because both systems are based on multiples often . Suppose you want to convert a length of 80 centimeters to meters . Follow these steps to convert between units . Begin by writing down the you want to this example , 80 centimeters . Write it conversion factor that represents the relationship between the two units you are converting . In this example . the ship is meter centimeters . Write this conversion factor as a fraction , making sure to place the units you are converting from ( centimeters . in this example ) in the denominator . Inquiry Skills To measure the temperature of in substance , you use the Celsius scale . Temperature is measured in degrees Celsius ( Ci using a Celsius thermometer . Water freezes at and boils at limo The unit scientists use to measure time is the second ( What is the temperature of the liquid in degrees Celsius ?

Multiply the measurement you want to convert by the fraction . When you do this . the units in the first measurement will cancel out with the units in the denominator . Your answer will be in the units you are ing to ( meters , in this example ) Example 80 centimeters I meters 80 centimeters centimeters meters Activity Convert between the following units . 600 millimeters I meters . liters I milliliters . grams I kilograms 511

Conducting a Scientific Investigation In some ways , scientists are like detectives . piecing together clues to learn about a process or event One way that scientists gather clues is by carrying out experiments An experiment tests an idea in I careful . manner . Although experiments do not all follow the some steps in the same order . many follow a pattern similar to the one described here . Posing Questions Experiments begin by asking a question is one that can be answered by gathering evidence . For example , the question Which freezes sh water or salt water ?

is question because you can carry out an and gather information to answer the question . Developing a Hypothesis The next step is to form a hypothesis . A hypothesis is a possible explanation for set of or answer to a question . A hypothesis may incorporate observations . concepts , principles . and theories about the natural world . Hypotheses lead to predictions that can be tested . A prediction can be worded as an if . statement . For example . a prediction might be If I add sub water , Iran the water will take longer iv freeze . prediction worded this way serves as rough outline of the experiment you should perform .

Designing an Experiment Next you need to plan a way to test your . Your plan should be written out as a procedure and should describe the or measurements you will make . Two important steps involved in designing an experiment are controlling variables and forming operational . Controlling Variables In a experiment . you need to keep all variables the same except for one . A variable is any factor that can change in an experiment . The factor that you change is called the manipulated variable . In this experiment . the manipulated variable it the amount of salt added to the water . Other factors . such as the amount of water or the starting temperature . are kept constant . The factor that changes as a result of the manipulated variable is called the responding variable . The responding variable is what you measure or observe to obtain your results . In this experiment , the responding variable is how long the water takes to freeze . An experiment in which all factors except one are kept constant is called a controlled experiment . Most controlled experiments include a test called the control . in this ment . Container is the control . Because no salt is added to Container you can compare the results from the other containers to it . Any erence in results must be due to the addition of salt alone . Forming Definitions Another important aspect ofa experiment is having clear operational . An operational is a statement that describes how a particular variable is to be measured or how a term is to be . For example . in this experiment , how will you determine if Lhe water has frozen ?

You might decide to insert a stick in each container at the start of the experiment . Your operational of frozen would be the time at which the stick can no longer move . Inquiry Skills of aal to I . no can to your . Interpreting Data The observations and measurements you make in an experiment are called data . At the end of an experiment . you need to analyze the data to look for any or trends . Patterns often become clear ifyou organize your data in a data table or graph . Then think through what the data reveal . Do they support your hypothesis ?

Do they point out a flaw in Do you need to collect more data ?

Drawing Conclusions A conclusion is a statement that sums up what you have learned from an experiment . When you draw a conclusion . you need to decide whether the data you collected support your hypothesis or not . You may need to repeat an experiment several times before you can draw any conclusions from it . Conclusions often lead you to pose new questions and plan new to answer them . Activity Is a ball bounce affected by the height from which it is dropped ?

Using the sup just described . plan a controlled experiment to investigate this problem . 523 Technology Design Skills Engineers are people who use and technological knowledge to solve practical problems . To design new products . engineers usually follow the process here , even though they may not follow these steps in the exact order . As you read the steps , think about how you might apply them in labs . Identify a Need Before engineers begin designing a new product . they must first identify the need they are trying to meet . For example . suppose you are at ber of a design team in a company that makes toys . Your team has at need a toy boat that is inexpensive and easy to assemble . Research the Problem Engineers often begin by gathering tion that will help them with their new design . This may include articles in books . or on the . It may also include talking to engineers who have solved similar problems . Engineer often perform experiments related to the product they want to design . For your toy boat . you could look at toys that are similar to the one you want to design . You might do research on the . You could also test some materials to sec whether they will work well in a toy boat . Drawing for a boat design Design a Solution Research gives engineers information that helps them design a product . When engineers design new products . they usually work in teams . Generating Ideas Often design teams hold meeting in which any team can contribute ideas . Brainstorming is at creative process in which one team member suggestions often spark ideas in other group members . Brainstorming can lead to new approaches to solving a design problem . Evaluating Constraints During storming , a design team will often come up with several possible designs . The team must then evaluate each one . As part of their evaluation . engineers consider constraints . Constraints are factors that limit or restrict a product design . ical characteristics , such as the properties of materials used to make your my boat . are constraints Money and time are also . If the materials in a product cost a lot , or if the product takes a longtime to make . the design may he . Making ! Design teams usually need to make . in a engineers give up one of a proposed design in order to obtain another . In designing your toy boat , you will have to make . For example . suppose one material is sturdy but not hilly waterproof . Another material is more proof , but breakable . You may decide to give up the benefit of in order to obtain the oi .

Build and Evaluate a Prototype Once the team has chosen a design plan . the engineers build a prototype of the product . A prototype is a working model used to test at design . Engineers evaluate the prototype to see whether it works well , easy to operate , is safe to use . and holds up to repeated use . Think of your my boat . What would the be like ?

materials would it be made ?

How would you test it ?

Troubleshoot and Redesign Few work perfectly . which is why they need to be tested . Once a design team has tested a prototype . the members analyze the results and identify any problems . The team then tries to troubleshoot , or the design problems . For example . if your toy boat leaks or wobbles . the boat should be redesigned to eliminate those problems . You can use the design process to design and build a toy boat . and Investigate . Visit the library or go to research toy boats . Investigate how a toy boat an be powered , Inquiry Skills Communicate the Solution A team needs to communicate the design to the people who will manufacture and use the product . To do this . teams may use sketches . detailed drawing . computer simulations . and word descriptions . includes a power system , a rudder , and an area for cargo travels meters in a straight line carrying a load of 20 pennies including wind . rubber bands . or baking soda . Sketch your design and write a and vinegar . plan for building your boat . After your teacher . Brainstorm materials , shapes . and steering for YOU . build YOU 508 ' your boat Evaluate and and Build . Test your boat . evaluate the results . and . Based on your research . design A toy boat that ' I is made of readily available materials 33 ' my boat to it performs better . is no larger than 15 long and 10 wide Skills 525

Creating Data Tables and Graphs How can you make unsc of tho data in I ?

The first step is to organize the data to help you understand them . Data tables and graphs are helpful tools for organizing data . Data Tables Calories Burned in 50 Minutes You have your materials and set up ri your experiment . But before you start . you , need to plan a way to record what happens i during the experiment . By creating at data table . you can record your observations and ' ments in an orderly way . EL , Suppose . for example . that a scientist an to out how many Calories people of different body masses burn while doing various activities . The data table number of Calories burned shows the results . while bicycling ) is the heading next Notice in this data table that the column . Additional columns were added for lated variable ( body mass ) is the heading ol related experiments . one column . The responding variable ( for Bar Graphs To compare how many a person burns . For each . draw a solid bar using the doing various activities . you could create a bar sail ! on the Vertical axis to determine the graph . A bar graph is to display data in a height . all the bars the same width . number of separate . or distinct . categories . Add ti um , this . bicycling . playing . and watching television are the three categories . Bumed by a , To create a bar graph follow these steps Perm i 30 I . On graph paper . draw a horizontal , or . axis and a vertical . or . axis . Write the names of the categories to be graphed along the horizontal axis . lnclude an overall label axis as well . Label the vertical axis with the name of the responding variable . Include units of . Then create a scale along the axis by marking off equally spaced numbers that cover the range of the data collected . Playing basketball television Activity 526

Line Graphs ' see whether a relationship exists between body mass and the number of Calories burned while bicycling , you could create at line graph . A line graph is used to display data that show how one variable ( the responding variable ) changes in response to another variable ( the manipulated variable ) You can use a line graph when your manipulated variable is continuous . that is , when there are other points between the ones that you tested . In this example . body mass is a continuous variable because there are other body masses between 30 and 40 grams ( for example . kilograms ) Time is another example of a continuous variable . Line graphs are powerful tools because they allow you to estimate values for conditions that you did not test in the . For ple . you can use the line graph to estimate that a person would burn 68 Calories while bicycling . To create ii line graph . follow these steps . I . On graph paper . draw a horizontal , or . aids and a vertical . or . Label the horizontal axis with the name of the manipulated variable . Label the vertical axis with the name of the responding able . lnclude units of . Create scale on each axis by marking off equally spaced numbers that cover the range of the data collected . Plot a point on the graph for each piece of data . In the line graph above , the dotted lines show how to plot the tirst data point ( 30 kilograms and 60 Calories ) Follow an imaginary vertical line extending up from the horizontal axis at the mark . Then follow an imaginary horizontal line extending across ( the vertical axis at the mark . Plot the point where the two lines intersect . Inquiry Skills Effect of Body Mass on Calories Burned While Bicycling In 30 Body Mass ) Connect the plotted points with a solid line . In some cases . it may be more appropriate to draw a line that shows the general trend of the plotted points . In those cases , some of the points may fall above or below the line . Also . not all graphs are linear . it may be more appropriate to draw a curve to connect the points . Add it title that the variables or relationship in the graph . Adi ity Club line graphs no display the data tram and Experiment In the data table . You read in the newspaper that a total at centimeters of rain fell in your area in June , fell in July , and fell in August . What type of graph would you use to display these data ) Use graph paper to create the graph . 521

Circle Graphs like bar graphs . circle graphs can be used to display data in a number of separate categories . Unlike bar graphs . however . circle graph can only be used when you have data for all the categories that make up a given topic . A circle graph is sometimes called a pie chart . The pie represents the entire topic . while the slices represent the individual categories . The size of a slice indicates what percentage ofthe whole a particular category makes up . The data table below shows the results of a survey in which 24 teenagers were asked to identify their favorite sport . The data were then used to create the circle graph at the right . Favorite Sports To create a circle graph . follow these steps . I . Use a compass to draw a circle . Mark the center with a point . Then draw a line front the center point to the top of the circle . Determine the sire of each slice by setting up it proportion equals the number of degrees in a slice . Note A circle contains 3641 degrees . For example . to the number of degrees in the soccer slice . set up the following proportion Students who refer soccer Total number Total in of students degrees In circle ?

and solve for . 24 360 The soccer slice should contain 120 degrees . 5280 Sports That Teens Prefer . Use a protractor to measure the angle of the first slice , using the line you drew to the top of the circle as the line . Draw a line from the center of the circle to the edge for the angle you measured . Continue around the circle by measuring the sire of each slice with the protractor . Start measuring from the edge of the previous slice so the wedges do not overlap . When you are done , the entire circle should be in . Determine the percentage of the whole circle that each slice . To do this . divide the number of degrees in a slice by the total number of degrees in a circle ( 360 ) and multiply by 100 . For the soccer slice . you can the percentage as follows . Use a different color for each slice . Label each slice with the category and with the percentage of the whole it represents . Add a title to the circle graph . In a class of 28 students , 11 students take the bus to school . 10 students walk , and students bicycles . Out I graph to display these data .

Math Skills Math Review Scientists use math to organize . analyze , and present data . This appendix help you review some basic math . Mean , Median , and Mode The mean is the average . or the sum of the data divided by the number of data items . The number in set of ordered data is called the median . The mode is the number that appears most often in a set of data . Probability A scientist counted the number songs sung by seven different male birds and collected the data shown below . Male Bird Songs Bird Number of songs 36 29 40 35 28 36 27 To determine the mean number of song . add the total number and divide by the number of data this case . the number of male birds . Mean ii 33 songs To the median number of songs . arrange the data in numerical order and Find the number in the middle of the series . 27232935363640 The number in the middle is so the median number of songs is 35 . The mode is the value that appears frequently . In the data , 36 appears twice , while each other item appears only once . Therefore . 36 songs is the mode . Find out how many minutes it takes each student in your class to get to school . Then the mean , median . and mode for the data . Probability is the chance that an event will occur . Probability can be expressed as a ratio . a fraction . or a percentage . For example , when you at coin . the probability that the coin will land heads up is in , or i , or St ) The probability that an event will happen can be expressed in the formula . Total number of wont A paper bag contains 25 blue marbles . green marbles , orange marbles . and yellow marbles . if you close your eyes and pick a marble from the bag . what is the probability that it will be yellow ?

marbles ) Each side ofa cube has a letter on il . Two sides have A , three sides have and one side has If you roll the cube . what is the probability that A will land on top ?

519 Area The men of a surface is the number of square units that cover it . The front cover of your book has an area of about 600 . Area of ti Rectangle and Square To the area of a rectangle . multiply its length times its width . The formula for the area oi rectangle is , Since all four sides of a square have the same length . the area of a square is the length ofone side multiplied by itself , or squared . A scientist is studying the plants in a field that measures 75 45 What is the area of the field ?

Ann of I The formula for the area of a circle is , The length ofthe radius is represented by and the value of it is approximately , Find the area ofa circle with a radius of 14 . Find the area of a circle that has a radius of Circumference The distance around a circle is called the circumference The for the circumference of at circle is The radius of it circle is 35 . What is its circumference ?

35 if 220 on What is the circumference ofa circle with a radius of 28 ?

Volume The volume of an object is the number of cubic units it contains . The volume of a , for example . might be about i Volume of Rectangular Object To find the volume of a obiect . multiply the objects length times its width times its height . wit Find the volume of box with length 24 . width 12 . and height . What is the volume of a rectangular object with length , width 11 . and height ?

Fractions A fraction is a way to express a part ofa whole . in the fraction . is the numerator and is the denominator . Adding and Subtracting Fractions To add or subtract two or more fractions that have a common denominator . first add or subtract the . Then write the sum or ence over the common denominator . To find the sum or of fractions with denominators . first find the least common multiple of the denominators . This is known as the least common denominator . Then convert each fraction to equivalent tions with the least common denominator . Add or subtract the . Then write the sum or difference over the common denominator . I ! TI ! Multiplying Fractions To multiply two fractions . multiply the two . then multiply the two denominators . Dividing Fractions Dividing by a fraction is the same as multiplying by its reciprocal . are numbers whose and denominators have been switched . To divide one by another . invert the fraction you are dividing other words . turn it upside down . Then multiply the two fractions . Solve the following unis Math Skills Decimals Fractions whose denominators are . or some other power of IO are often ex as decimals . For example . the fraction can be as the decimal , and the fraction can be written as . Adding and Subtracting With Decimals To add or decimals . line up the mal points before you carry out the operation . Multiplying with Decimals When you multiply two numbers with decimals . the her of decimal places in the product is equal to the total number of decimal places in each number being multiplied . one decimal place ) two decimal pious ) three decimal plans ) Dividing With Decimals To divide a decimal by a whole number . put the decimal point in the quotient above the decimal point in the dividend . To divide at decimal by a decimal . you need to rewrite the divisor as a whole number . this by multiplying both the divisor and dividend by the same multiple of It ) Prat lit ?

Multiply by . Skill 531 Ratio and Proportion A ratio compares two numbers by division . For example . suppose a scientist counts 800 wolves and moose on an island . The ratio of wolves to moose can be written as fraction . which can be reduced to The same ratio . A proportion is it mathematical sentence saying that two ratios are equivalent . For example . a proportion could state that You can sometimes set up a proportion to determine or estimate an unknown quantity . For example . suppose a counts 25 beetles in an area of IO square meters . The scientist wants to estimate the number of beetles in 100 square meters . Express the hip between beetles and area as a ratio to . Set up a proportion . with representing the number of beetles . The can be stated as . Begin by . other words , multiply each fractions tor by the other denominator . To the value of divide both sides by . The result is or 250 beetles in 100 square meters . Find the value of in the following proportion Percentage A percentage is a ratio that compares a ber to . For example . there are 37 granite rocks in at that consists of rocks . The ratio 14 can be written as 37 . Granite rocks make up 37 of the rock collection . You can calculate percentages of numbers other than by setting up a proportion . Rain falls on days out of 30 in lune . What percentage of the days in were rainy ?

aways roost To find the value of begin by multiplying . as for any proportion There are 300 marbles in a jar . and 42 of those marbles are blue . What percentage of the marbles are blue ?

Significant Figures The precision of a measurement depends on the you use to take the measurement . For example . if the smallest unit on the ruler is millimeters . then the most precise measurement you can make will be in millimeters . The sum or difference of measurements can only be as precise as the least precise ment being added or subtracted Round your answer so that it has the same number of digits after the as the least precise ment . Round up if the last digit is or more . and round down if the last digit is or less . Subtract a temperature of from the temperature . has the fewest digits after the decimal . so it is the least precise measurement . Since the last digit ol the answer is , round up to . The most precise difference between the measurements is . Add to in . Round your answer according to the precision of the measurements . are the number of digits in a measurement . between digits are also . For example , the measurements . and all have three . When you multiply and divide measurements , the one with the fewest determines the number of in your answer . Multiply 110 by 110 Because has only two , round the answer to 630 Math Skills Scientific Notation A factor is a number that divides into another number with no remainder . in the example . the number is used as a factor four times . An exponent tells how many times a number is used as a factor . For example . can be written as . The exponent indicates that the number is used as a factor four times Another way of expressing this is to say that ill is equal to to the fourth power . notation uses exponents and powers of ten to write very large or very small numbers in shorter form . When you write a number in notation . you write the number as two factors . The first factor is any number between and 10 . The second factor is a power of such as 10 or . The average distance between the planet Mercury and the sun is ( To write the factor in notation . insert a decimal point in the original ber so that you have a number between I and in the case of . the number is . To determine the power of count the number of places that the decimal point moved this case . it moved places . tun 107 Express irt notation . Skill 533