What is Science?• Science: Process that produces

information about the natural world

• Steps: Observation & Experimentation

• Why: Apply the results improve understanding of the natural world.

• Why: Better understand our world

• Standadized way of gathering information by repeatable method. by the “Scientific Method”

• Definition: A 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 observation

– Example: Why is there little ground vegetation in this forest?

• 2nd step: Create a hypothesis

– If…then statement

– Example: If there are tall trees blocking sunlight, then few plants will gro

• Or create multiple hyphotheses to see which better explains the data

3rd step: Design an Experiment

1) Control group:• comparison group• All variables are held

constant

2) Experimental group: •Test Group•All variables identical to the control group, except one independent variable is changed.

Experiments test the difference between a control group and an experimental group.

Question: •Why is there little ground vegetation in this forest?

Hypothesis:•Large trees block light from reaching the ground, so few plants can grow at ground level.

Dependent variable is the variable that is intentionally manipulated.

Design the ExperimentControl Group: •Patch of forest with large canopy trees

Experimental group: •Patch in a forest where there are no large canopy trees

•Independent variable: trees or no trees•Dependent variable: number and growth of ground plants

Control Group Experimental Group

6 hours sun/day 6 hours sun/day8cm rain/month 8cm rain/month

Grazing animals Grazing animals60⁰ temp 60⁰ temp

Large canopy trees Patch of open land

• Why is this a good experimental design?

• The experimental plants grew 1 meter taller. What most likely caused this change?

Control Group Experimental Group

6 hours sun/day 8cm rain/month 8cm rain/month

Grazing animals Grazing animals60⁰ temp

Large canopy trees Patch of open land

• Why is this a good experimental design?

• The experimental plants grew 1 meter taller. What most likely caused this change?

80⁰ temp

4 hours sun/day

Control Group Experimental Group

6 hours sun/day4 hours sun/day

8cm rain/month 8cm rain/month

Grazing animalsGrazing animals

60⁰ temp 80⁰ temp

Large canopy trees Patch of open land

• This is a poor experimental design. Why?• What most likely caused the change in growth of ground plants?

4th Step: Data Analysis

• Collect data to either support/reject your hypothesis– Ex: Plants on the ground grew almost 1m taller w/o the

canopy trees– No hypothesis is proven after 1 experiment

00.20.40.60.8

11.21.4

Heig ht (meters )

with large trees without large trees

P lant G rowth

5th 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

Farmer Bob wants to test his 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 but adds no fertilizer. In section B, he waters his crops as usual and also adds his 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 BSubstance added to the crops

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 sleepAmount 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 studentsTeaching 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 weekLength of practice

Goals scored per game

The city of Los Angeles wants to know if there is a connection between physical fitness and air pollution. Fifty volunteers from the mayor’s office agree to be tested. First, they are asked to ride a stationary bike for 1 hour in a pollution-free air chamber. A week later, the 50 volunteers return and are again asked to ride a stationary bike for 1 hour in a chamber filled with air pollutants common to Los Angeles. Their heart rates are monitored throughout the 1 hour bike rides.

Name the control group _________________________________________________

Name the experimental group ____________________________________________

Name the independent variable __________________________________________

Name the dependent variable ____________________________________________

Volunteers who breathed common polluted air

Volunteers who breathed clean airQuality of air breathed

Heart rates

Quiz1) 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) What is the data collected from the independent variable called?