Scientific Method S. Burnham Biology

Scientific Method Certain methods to obtain knowledge Certain methods to obtain knowledge Ask questions, make observations, ascertain explanations Ask questions, make observations, ascertain explanations 7 Steps 7 Steps Have you ever asked who, what, where, when, how, or why? That’s the beginning. Have you ever asked who, what, where, when, how, or why? That’s the beginning.

Steps in the Scientific Method 1. Use observations to identify a problem 2. Formulate a hypothesis 3. Construct a procedure (step by step directions) 4. Conduct your experiment 5. Collect and analyze data 6. Draw a conclusion 7. Repeat

Step 1: Use observations to identify a problem Observation Raises questions Raises questions Employs one or more of the 5 senses to perceive objects or events Employs one or more of the 5 senses to perceive objects or events Direct (hear a animal call in the wild) or indirect (examining electricity) Direct (hear a animal call in the wild) or indirect (examining electricity)

Step 2: Formulating a Hypothesis Statement that explains their observations and can be tested Statement that explains their observations and can be tested If testable, evidence can be collected that either does or does not support the statement If testable, evidence can be collected that either does or does not support the statement IF (put independent variable here), THEN (put dependent variable here) statement IF (put independent variable here), THEN (put dependent variable here) statement If the virus causes a deadly disease then introducing that virus into healthy tissue will cause the tissue to die. If the virus causes a deadly disease then introducing that virus into healthy tissue will cause the tissue to die. Not all hypotheses are in If, then format. Not all hypotheses are in If, then format.

Independent vs. Dependent Independent is manipulated variable (what you change) Independent is manipulated variable (what you change) Dependent is responding variable (what happens due to the change) Dependent is responding variable (what happens due to the change) REMEMBER: REMEMBER: D – dependent R – responding Y – axis M – manipulated I – independent X – axis

Step 3: Procedure Step by step directions that are self explanatory Step by step directions that are self explanatory Number your steps Number your steps Be specific about equipment, amounts, units, etc… but not wordy Be specific about equipment, amounts, units, etc… but not wordy

Step 4: Experimenting Process of testing a hypothesis by gathering data under controlled conditions Process of testing a hypothesis by gathering data under controlled conditions Controlled Experiment You change one factor or variable and observe its effect on another while keeping all other factors the same or constant You change one factor or variable and observe its effect on another while keeping all other factors the same or constant

Experimenting cont… Variable: factors that can be changed 2 types: 2 types: 1. Dependent/Responding Variable: what is being measured ex. Height, growth, amount of oxygen produced, etc. ex. Height, growth, amount of oxygen produced, etc. 2. Independent/Manipulated Variable: what you change on purpose ex. Light exposure, food, time, depth, scent, etc. ex. Light exposure, food, time, depth, scent, etc.

Experimenting cont… Constant: variables that stay the same through out the experiment ex. Same amount of water in all beakers, same sized beakers, same plants… Control: a sample that is treated like the other experiment groups but the independent variable isn’t applied (what normally takes place) ex. You are testing a new drug. One group received the drug; the other group was a placebo (sugar pill). The group given the placebo is the control group.

Scenarios As a group, analyze the scenarios to come up with: As a group, analyze the scenarios to come up with: What is the question being raised? What is the question being raised? Independent Variable? Independent Variable? Dependent Variable? Dependent Variable? Control? Control? Constant(s)? Constant(s)? Write a hypothesis based on the scenario. Write a hypothesis based on the scenario.

Step 5: Collecting and analyzing data Forms of Data Collection: 1. Measuring Quantitative data: data is measured in numbers Quantitative data: data is measured in numbers Number of people in a group Number of people in a group Measurements of a cube Measurements of a cube Duration of an event Duration of an event 2. Sampling Using a small part to represent an entire population Using a small part to represent an entire population Must be large and random Must be large and random Should include as many subjects as possible Should include as many subjects as possible

Forms of Data Collection cont… 4. Organizing Data Data is useless unless its organized Data is useless unless its organized Data table, graphs, chart, concept map (appendix A) Data table, graphs, chart, concept map (appendix A)

Analyzing Data Process of determining whether data you collected is reliable and if it supports your hypothesis or not Process of determining whether data you collected is reliable and if it supports your hypothesis or not Data can be analyzed in several ways Data can be analyzed in several ways Statistics to determine a relationship between the variables Statistics to determine a relationship between the variables Compare the data with those obtained in other trials or studies Compare the data with those obtained in other trials or studies Determine sources of error Determine sources of error

Analyzing Data cont. Data analysis shows general or specific trends or patterns from a graph that you have created from your data chart or table. Data analysis shows general or specific trends or patterns from a graph that you have created from your data chart or table. General Trend: From 1955 to 1995, the total amount of ozone decreased from 325 d.u. to 169 d.u. in Antarctica. Specific Trend: From1964 to 1966, the total amount of ozone increased from 280 d.u. to 320 d.u. in Antarctica.

Step 6: Drawing Conclusions 1. Create a Model Constructing a representation of an object or process that shows a relationship among the data Constructing a representation of an object or process that shows a relationship among the data Visual, verbal or mathematical Visual, verbal or mathematical 2. Inferring Conclusion made on the basis of the facts or data gathered during your experiment Conclusion made on the basis of the facts or data gathered during your experiment 3. Forming a Theory May be formed after many related hypothesis have been tested and supported by much experimental data May be formed after many related hypothesis have been tested and supported by much experimental data Broad and comprehensive statement that is thought to be true Broad and comprehensive statement that is thought to be true

Step 7: Repeat! Make sure the data is accurate (you can reproduce it) Precision: how close you are to the actual number

Ticket out the door Individually answer the questions to Dog Licking its Wound and turn in before leaving the class today. Individually answer the questions to Dog Licking its Wound and turn in before leaving the class today.