Intro to BiologyIntro to BiologyUnit 1 (Chapter 1) Unit 1 (Chapter 1) The Basis of LifeThe Basis of LifeScientific MethodScientific Method

The Scientific MethodThe Scientific Method

What is science?What is science?

What is the scientific method?What is the scientific method?

Determining variables in an experimentDetermining 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

1st step: Make an observationExample: Why is there little ground

vegetation in this forest?

2nd step: Create a hypothesis If…then statementExample: If there are tall trees

blocking sunlight, then few plants will grow near the ground.

3rd 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 Group Experimental Group

6 hours sun/day 6 hours sun/day8cm rain/month

8cm rain/month

Grazing animalsGrazing animals60⁰ temp

60⁰ temp

Large canopy trees Patch 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 Group Experimental Group

6 hours sun/day4 hours sun/day8cm rain/month

8cm rain/month

Grazing animalsGrazing animals60⁰ temp 80⁰ temp

Large canopy trees Patch 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

4th Step: Data Analysis

Collect data to either support/reject your hypothesisNo hypothesis is supported/rejected after ONE experimentCANNOT be PROVED only tested!

00.20.40.60.8

11.21.4

Heig ht (meters )

with large trees without large trees

P lant G rowth

5th Step: ConclusionYour findings could be shared and

repeated by others

Theory develops over timeTheory = 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