Intro to Biology Unit 1 (Chapter 1) The Basis of Life Scientific Method

The Scientific Method What is science? What is science? What is the scientific method? What is the scientific method? Determining variables in an experiment Determining variables in an experiment

What is Science? Science: Process that produces information about nature Steps: Observation & Experimentation Why: Apply the results to the real world Why: Better understand our world

Defined: Series of steps to collect information or solve problems 1) Observation 2) Hypothesis 3) Experimentation 4) Data Analysis 5) Conclusion Scientific Method

Observation and Hypothesis 1 st step: Make an observation Example: Why is there little ground vegetation in this forest? 2 nd step: Create a hypothesis If…then statement Example: If there are tall trees blocking sunlight, then few plants will grow near the ground.

3 rd step: Design an Experiment Two parts to an experiment: 1)Control group  Receives no special treatments  Used as comparison  The “normal” group 2) Experimental Group  Receives the treatment  Contains the independent variable  Independent variable = one factor that differs from the control group  Data collected is called the dependent variable

Here is a well designed setup

Control GroupExperimental Group 6 hours sun/day 8cm rain/month Grazing animals 60 ⁰ temp Large canopy treesPatch of open land The experimental plants grew 1 meter taller. What most likely caused this change? What are the constants?

Here is a poorly designed setup

Control GroupExperimental Group 6 hours sun/day 4 hours sun/day 8cm rain/month Grazing animals 60 ⁰ temp 80 ⁰ temp Large canopy treesPatch of open land The experimental plants grew 1 meter taller. What most likely caused this change? Unknown! Too many changed variables!

Farmer Bob wants to test a new fertilizer to help his crops grow better. He sections off two large areas of his field. In section A, he waters his crops as usual and uses his normal fertilizer. In section B, he waters his crops as usual and but adds the experimental fertilizer. After 1 growing season, he records the growth of the crops. Name the control group _________________________________________________ Name the experimental group ____________________________________________ Name the independent variable __________________________________________ Name the dependent variable ____________________________________________ Section A Section B Type of fertilizer used Growth of the crops

The United States military wants to see if soldiers with only 4 hours of sleep can operate at the same level as those who normally get 7 hours of sleep. One hundred solders are allowed to only sleep for 4 hours a night and another hundred are allowed to sleep for 7 hours a night. During the day, the soldiers are tested for marksmanship on the firing range. Name the control group _________________________________________________ Name the experimental group ____________________________________________ Name the independent variable __________________________________________ Name the dependent variable ____________________________________________ Soldiers with 7 hours sleep Soldiers with 4 hours sleep Amount of sleep given Score on the firing range

A teacher wants to know if her new teaching method is more successful than traditional teaching methods. She compares test scores of her period 2 class (received the traditional teaching method) verses her period 4 class (received new teaching method). Each class has a random mix of honors students. Name the control group _________________________________________________ Name the experimental group ____________________________________________ Name the independent variable __________________________________________ Name the dependent variable ____________________________________________ Period 2 students Period 4 students Teaching method Test scores

A high school soccer team on average scores 2.2 goals per game by practicing 4 days a week. The coach wants to see if practicing 5 days a week will help the team score more goals. The coach has the team practice 5 days per week and compares the goals scored per game. Name the control group ___________________________________________ Name the experimental group ______________________________________ Name the independent variable ____________________________________ Name the dependent variable ______________________________________ Practicing 4 days per week Practicing 5 days per week Length of practice Goals scored per game

4 th Step: Data Analysis Collect data to either support/reject your hypothesis No hypothesis is supported/rejected after ONE experiment CANNOT be PROVED only tested!

5 th Step: Conclusion Your findings could be shared and repeated by others Theory develops over time Theory = long standing hypothesis Theories and hypotheses change based on new information

Review 1)Place the 5 steps of the scientific method in order from start to finish. Data analysis, Observation, Conclusion, Experimentation, Hypothesis 2)In which stage of the scientific method are graphs usually created? 3)In which stage of the scientific method are the two variables identified? 4)Which variable is the difference between the control and experimental group? 5)Which group of an experiment is used for comparison and contains no changes? 6)How many independent variables should exist in a well designed experiment? 7)Vocabulary: Science, Scientific method, Hypothesis, Control group, Experimental group, Independent variable, Dependent variable, Theory