Scientific Method Science is ultimately based on observation –Sight and hearing Observations will lead to question—which lead to experiments to answer the questions What is the Scientific Process? –Observations –Questions –Hypothesis (prediction) –Experimentation –Record and analyze results –Conclusions

Observation and Question Observation –My plants aren’t growing very well Question –What if I used Miracle Grow to increase my plants growth

Hypothesis What is a hypothesis? –A testable statement, can be shown to be true or false by experimenting or observation –A proposed scientific explanation for a set of observations that may be disproved by a single experiment –If than statement –Examples Plants will grow taller when given Miracle Grow Girls will score higher on math tests than boys Hermit crabs choose colorful shells over drab shells

Spontaneous Generation Spontaneous generation (hypothesis) that life can rise from nonliving matter Redi’s Experiment on spontaneous generation- flies produce maggots Anton van Leeuwenhoek-discovered animalcules John Needham-claimed spontaneous generation could occur under right conditions Lazzaro Spallanzani-concluded that nonliving gravy did not produce living things Louis Pasteur-finally disproved spontaneous generation

Experiment A hypothesis is then tested by experimentation- a planned procedure designed to test the hypothesis Controlled experiment- only one variable is changed at a time, other variables are kept constant Experimental group receives some kind of treatment or condition Control Group receives no treatment, used to compare Everything about the two groups except the factor you are testing must remain exactly the same –Why?

Example of an Experimental Design Hypothesis: Plants will grow taller when given Miracle Grow Plants A & B are both given the same amount of light, water, and are stored at the same temperature. Plant A is given Miracle Grow –All the variables are kept constant except the one you are testing

Experimental Design Independent Variable or manipulated variable –The factor you change, what you do to your experimental group –What is ours? Miracle Grow Dependent variable or responding variable –What happens as a result of that treatment, what you are measuring –What is ours? Height of Plant

Collecting Data Need to put data into data tables or graph charts A scientist carefully collects and organizes data from the experiment. Data should always be presented in a neat fashion, usually tables or graphs

Collecting Data

Conclusions Based on the data, you then determine whether the hypothesis was supported or refuted. Can’t prove something, nothing is absolute in science The conclusion is only “true to the best of our knowledge” Science is subject to change when new evidence is found Experimentation and observations can provide strong evidence for a conclusion, but not absolute proof

Theory What is a theory? –An explanation for natural events that is based on a large number of observations –Becomes a theory when enough experimental data supports a hypothesis –Theories explain what we observe –They are changeable and expandable, most importantly, theories are FALSIFIABLE Able to be shown to be incorrect by observation or experimentation