Scientific Method, Measurements and the Metric System Methods of Science Scientific Method, Measurements and the Metric System

What is Science? Science Process that uses observation and investigation Used to gain knowledge about events around us Latin word scientia = knowledge

Major Categories of Science Life Science Living things Earth Science Investigates Earth & space Physical Science Matter and energy

Scientific Method Scientific Method Organized set of investigation procedures 6 steps Some steps repeated or skipped during an investigation

Scientific Method Observe a problem Gather info Hypothesis Experiment Possible explanation Experiment Test Analyze data Draw conclusion REPEAT !!!!

Variables in an Experiment Must be in a controlled environment Usually consists of two variables Variable = quantity that can have more than one value

Dependent vs. Independent Independent variable Variable in the experiment you change What is being tested Dependent variable Value changes according to the independent “depends” on the independent What you are measuring

Constant and Controls Constant Variables Control Group Factors in the experiment that does not change Allows for a “fair” test Control Group Standard by which results can be compared

For Example: Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. Independent = ??? (What is being tested; changed?) Dependent = ??? (What are you measuring?) Controlled = ??? (What variable stayed the same?)

For Example: Students set up an experiment to determine which of three fertilizers helps plants grow taller. Independent? Dependent? Control Variables?

Independent vs. Dependent Extra Practice Identifying Independent vs Dependent Variables

Standards of Measurement Exact quantity used to compare measurements U.S. uses English system standards & metric standards Most other nations . . . all metric system Metric & Standard Measurement Systems English Vs. Metric System Yards vs. Meters Gallons vs. Liters Pounds vs. Grams Miles vs. Kilometers Fahrenheit vs. Celsius

Metric System SI System System International Aka metric system Accepted by scientist throughout the world Uses a base unit with prefixes Based on units of 10 Why science uses the metric system.

Metric System Base Units Meter measures length Liters measures volume Gram measures mass Second measures time Celsius/Kelvin measures temp

Metric Prefixes Metric Prefixes Use prefixes with base units Kilo = 1000 Hecto = 100 Deca = 10 Base Units (g, L & m) = 1 Deci = 1/10 Centi = 1/100 Milli = 1/1000 Metric System Rap

Metric Prefixes

Length Length Distance between two points Metric base unit is the meter Use metric prefixes according to what you’re measuring Use ruler, meter stick or tape measure to find lengths of objects

Volume Volume Amount of space occupied by an object Volume of a liquid is measured with base unit Liter Volume of a solid is measured with unit of length Length x Width X Height L(1) x L(2) x L(3) Unit of length³

Volume Volume of a liquid Volume of a solid Use graduated cylinders for precise volume Beakers for accurate volume Volume of a solid Use ruler or meter stick to measure 3 dimensions

Volume Volume Equivalencies 1 cm³ = 1 mL = 1g 1,000 cm³ = 1 L

Mass Mass Amount of matter in an object Metric base unit is the gram Use triple beam balance or electronic balance when measuring mass

Density Density The mass per unit volume of an object Density equals mass of an object divided by the volume D = m/v Unit for density is g/cm³ OR g/mL Density < 1 object floats Density > 1 object sinks

Time and Temperature Time Temperature Interval between two events Unit of measurement is seconds Temperature How hot or cold something is Unit of measurement is °Celsius or °Kelvin

Temperature Conversions Temp Conversions Water boils at 100° C and 212° F Water freezes at 0° C and 32°F C = (F – 32) x .56 F = (C x 1.8) + 32

Example Problems Find the volume of a box that has a length of 2.3 mm, height of 3.4 mm and a width of 2.1 mm. 2. Find the width of a container that has a volume of 120 cm³, length of 10 cm and height of 5 cm. 3. Find the density of an object that has a mass of 2.1 mg and volume of 9.2 mm³. 4. Find the mass of an object that has a density of 0.78 g/ml and a volume of 16 ml.

Example Problems 1. Convert the following: 97° F to C 12°F to C 45° C to F 97° F to C 12°F to C 65° C to F