Scientific Method Systematic approach used in scientific studies A logical approach to solving problems by observing and collecting data, formulating a hypothesis, testing a hypothesis, and formulating theories that are supported by data
Steps of the Scientific Method • Observation • Problem Statement • Hypothesis Statement • Experiment / Data Collection • Conclusion Statement
Types of Observation Qualitative Data and observations (QL) Color, shape, odor, or other physical characteristics Quantitative Data and observations (QN) Numerical information such as temperature, pressure, volume, the quantity of a chemical formed
Variables Independent Variable (IV) aka manipulated variable Only ONE!!! The one the INDividual (YOU) physically change/manipulate Dependent Variable (DV) aka the responding variable Only ONE!!! The one that changes (or you hope will change) when you change the IV The one you are collecting data about/measuring Constant Variables MANY of these All the things you want to keep the SAME (do NOT change)
Variables You should be able to identify the IV and DV from your PS!!!!
Formula: If…(state what will be done to the IV), then…(state what is predicted to happen to the DV)
CLASS WORKName That Variable!Control (1):Constants(2) :Independent (1): Dependent (1):Hypotheses (1): 1. An experiment that tests how quickly different temperatures will dissolve sugar cubes. 2. An experiment that explores how different colors of light impact plant growth. 3. How does the temperature of a chemical reaction change over time?
Experiment a planned way to test a hypothesis and find out the answer to the problem statement. a way to collect data and determine the value of the DV. compares the IV to the DV. can only test one DV at a time and change one IV at a time
Experiment Variables Materials and Procedures Data and Results Section Include observations (QL and QN) Pictures/tables/graphs/calculations
Why Do We Use Graphs? Graphs help us visualize numerical data. •There are several different types of graphs: Bargraphs: compare multiple objects Piegraphs: shows relationships of parts to a whole Linegraphs: show the relationship between 2 variable
Types of Relationships (between variables) Direct: as x increases y increases Indirect: as x increases y decreases Constant: as x increases y remains the same
Conclusion Statement Do NOT use 1st person Me, my, I, we, our, etc… VERY Objective a summarization that presents the findings of the experiment, what the data shows, and states if the hypothesis was correct (supported) or incorrect (negated) Restate PS Restate HYP Summarize M&P Analyze and explain data/results (tables, observations, pictures) State whether HYP was correct or not and EXPLAIN why Explain possible errors Explain ways to improve experiment/research Explain APPLICATION to biology and society
After we accept a hypothesis, experiment, and draw a conclusion… Many conclusions that support each other make up a THEORY Explanation supported by many, many conclusions Many conclusions that support each other over a period of time Atomic Theory Theory of Relativity CAN be DISPROVEN “The world is flat” SCIENTIFIC LAW A relationship in nature that is supported by many, many experiments No exceptions Law of Gravity
SI Units In science, we need to speak the same language 1795 French scientists develop metric system 1960 International committee meets to update the system and names it the “Systeme Internationale d’Unites” aka SI
SI Base Units Seven SI base units Base unit A defined unit in a system of measurement that is based on an object or event in the physical world
SI Derived Units Not all quantities can be measured with base units More than one base unit can be used Speed limit is measure in…. MPH Miles per hour Which is a combo of what base units? Length and time
Common derived units we will use Speed Base unit of length and base unit of time Meters/second Volume 3 base units of length Length x length x length 1 dm3 = 1 L Density Mass/volume Ratio that compares mass of an object to its volume g/cm3 or g/mL
Class Work! Suppose a sample of aluminum is placed in a 25 mL- graduated cylinder containing 10.5 mL of water. The level of water rises 13.5 mL. Mass is 25 g. What is the density of the aluminum sample? What is the volume of a sample that has a mass of 150 g and a density of 5 g/mL?