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

• Information gathered by the “Scientific Method”

Scientific Method• Defined: Series of

steps to collect information and solve problems

1) Observation2) Hypothesis3) Experimentation4) Data Analysis5) Conclusion6) Replication

Observation and Hypothesis• Observe the living world

– Example: Very little plant life on a forest floor

• Hypothesis: tentative explanation– If…then statement– Example: If there are tall

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

Experimentation• Experiment will test your

hypothesis• Two parts to an experiment

o 1) Control group: patch of land with the large canopy trees

o 2) Experimental group: patch of land w/o canopy trees

• Caution! Two groups must differ by only 1 factoro Independent variable: factor

you are testing (Ex: Presence of the canopy trees)

o Dependent variable: factor you measure (Ex: growth of the plants)

Here is a well designed setup

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

Here is a poorly designed setup

Control Group Experimental Group

6 hours sun/day 4 hours sun/day8cm rain/month 8cm rain/month

Grazing animals Grazing animals60⁰ temp 80⁰ temp

Large canopy trees Patch of open land

Data Collection

• Collect data to either support/not support your hypothesis– No hypotheses are proven after 1 experiment

• Data and Results: Plants on the ground grew almost 1m taller w/o the canopy trees

Conclusion & Replication• Your findings would be

shared and duplicated by others

• Develop a THEORY (hypothesis that has been tested and continually supported)

• Theories and hypotheses change based on new information

Quick Review• Science tries to explain the

natural world• Science is made through

observation and experimentation• Science is continually changing

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 B

Chemical 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.

Soldiers with 7 hours sleep

Soldiers with 4 hours sleep

Amount of sleep given

Name the control group _________________________________________________Name the experimental group ____________________________________________Name the independent variable __________________________________________Name the dependent variable ____________________________________________Score on the firing range

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.

Volunteers who breathed common polluted air

Volunteers who breathed clean air

Quality of air breathedHeart rates

Name the control group _________________________________________________Name the experimental group ____________________________________________Name the independent variable __________________________________________Name the dependent variable ____________________________________________