CHEMISTRY 4 The fourth step of the scientific method is gathering materials hypotheses in experiments and then testing the hypothesis Scientists test or try out their Scientists conduct the same experiment many times to be sure of the results Scientists often do their experiments in a laboratory A laboratory is a place where scientists conduct experiments and collect data Controlling conditions in a laboratory is easier than controlling conditions in the real world For example temperature levels are able to remain constant in a controlled setting That would be impossible to do outside of a laboratory Y R T S I M E H C S I T A H W 6 A scientist carefully records data during an experiment 3 The third step of the scientific method is making a thoughtful hypothesis is an idea or opinion based on some data or observations but not proven guess or hypothesis A Scientists formed the hypothesis that this fertilizer is what makes the plants grow big and healthy They will test their hypothesis to see if it is true
7 CHEMISTRY W H A T I S C H E M I S T R Y Chemists made sure this medicine was safe for children HOW DO SCIENTISTS LEARN ABOUT CHEMISTRY They observe or watch substances They do experiments They try to make substances change and then record what happens An experiment might show that the hypothesis is not correct For this reason scientists always perform tests for one experiment several times They call these tests trials In each trial scientists change only one thing also known as the variable New data might cause a scientist to change the hypothesis Sometimes a scientist disregards the hypothesis and starts all over Hypotheses proven true predict how things will work and can be very helpful control kuhn-TROHL to exercise restraint or direction over dominate command experiment ek-SPER-uh-ment a scientific test to try out a theory or to see the effect of something fuel FYOO-uhl something that is used as a source of heat or energy such as coal wood gasoline or natural gas observation ob-zur-VAY-shuhn the careful watching of someone or something
CHEMISTRY (cid:55)(cid:75)(cid:72)(cid:85)(cid:72)(cid:3)(cid:68)(cid:85)(cid:72)(cid:3)(cid:20)(cid:15)(cid:19)(cid:19)(cid:19)(cid:3)(cid:80)(cid:76)(cid:79)(cid:79)(cid:76)(cid:80)(cid:72)(cid:87)(cid:72)(cid:85)(cid:86)(cid:3)(cid:298)(cid:80)(cid:80)(cid:299)(cid:3)(cid:76)(cid:81)(cid:3) 1 meter There are 1,000 meters in a (cid:78)(cid:76)(cid:79)(cid:82)(cid:80)(cid:72)(cid:87)(cid:72)(cid:85)(cid:3)(cid:298)(cid:78)(cid:80)(cid:299)(cid:17) Doctors measure your height in the standard unit of inches Scientists measure height in the metric unit of centimeters Unit of Measurement Abbreviation millimeter centimeter meter kilometer mm cm m km Things You Might Measure With This Unit ant small button or end of an eraser hamster length of your foot or the length of a gecko lizard distance between your classroom and the lunchroom or the length of a Komodo dragon or a whale distance of a marathon or the distance between two cities Measurement Y Scientists use the metric system People can describe the world in many ways They can say how big something is how much it weighs or how hot it feels They can use measurements to describe these things to measure distance and length They measure distance and length using a metric ruler tape measure or other special tools A meter is a specific unit of measurement A meter can be broken down into smaller parts called centimeters and millimeters There are (cid:20)(cid:19)(cid:19)(cid:3)(cid:70)(cid:72)(cid:81)(cid:87)(cid:76)(cid:80)(cid:72)(cid:87)(cid:72)(cid:85)(cid:86)(cid:3)(cid:298)(cid:70)(cid:80)(cid:299)(cid:3)(cid:76)(cid:81)(cid:3)(cid:20)(cid:3)(cid:80)(cid:72)(cid:87)(cid:72)(cid:85)(cid:3)(cid:298)(cid:80)(cid:299)(cid:17)(cid:3) R T S I M E H C S I T A H W 8
CHEMISTRY Unit of Measurement Abbreviation kilogram gram milligram kg g mg Things You Might Measure With This Unit yourself or a dog a bag of apples or a box of cookies a paper clip or a baby tooth Scientists use grams or milligrams to measure the weight of something Scales are instruments used to measure weight Scientists use scales that weigh in kilograms grams or milligrams What’s the Difference Between Mass and Weight Weight is the measure of how strongly gravity pulls on matter Mass is the measure of how much matter an object has If you were to go to the Moon your weight would change because the pull of gravity on Earth is stronger than on the Moon Your mass would not change because you would still have the same amount of matter This scale measures in the standard unit of pounds or the metric unit of kilograms W H A T I S C H E M I S T R Y 9
