1. Hypotheses, Models, Theories, and Laws
SC.8.N.3.2/ SC.7.N.3.1
The scientific method is the model used to help scientists gather data to support a hypothesis or theory. The words hypothesis, theory, and law have very different meanings but are grounded by empirical observations that are testable. Today we’re going to discus those definitions in more details.

2. HYPOTHESES
A statement that predicts the cause and effect of the area of concern. The prediction is usually driven by prior knowledge or personal experiences.
The most difficult step of the scientific method is developing a testable hypothesis. This type of hypothesis is a statement that predicts the cause and effect of the area of concern. The prediction is usually driven by prior knowledge or personal experiences. A hypothesis can be supported or it may fail to be supported by experimentation or observations. A hypothesis can be disproven, but it can never be proven to be true. Furthermore, a hypothesis is determined to be valid after extensive experimentation, observations, and data analysis yet, can later be disproven when new knowledge or technology becomes available.

3. MODELS
A model is used when it is too difficult to test the hypothesis and is impossible to be proven as true.
A model is a representation of a hypothesis that is useful in helping experimenters better understand a system or an arrangement. A model is used when it is too difficult to test the hypothesis and is impossible to be proven as true. The Bohr model of an atom, the model of the arrangements of the planets, and models of cells are examples of times when experimenting becomes almost impossible.

4. What is a Theory in Science?
Explains a natural phenomenon.
Predicts future occurrences or observations of the same kind.
Can be tested through experiment or otherwise verified through empirical observation.
Is Supported by a vast body of reliable knowledge.

5. Once a hypothesis is verified,
THEORIES
Once a hypothesis is verified,
it becomes a theory.
Once a hypothesis is verified, it becomes a theory. Many people define a theory as an accepted hypothesis that has proven consistent over time and through many investigations. Theories are valid as long as there is no evidence that disproves it. It is very difficult and timely to get the scientific community to change their views on a scientific theory once it has been disproven.

6. EXAMPLES OF THEORIES
The Big Bang Theory proposes that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion.
1- The Big Bang Theory proposes that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion.
2- Theory of Plate Tectonics explains the structure of the earth's crust and the changes that result from the lithospheric plates that move slowly over the underlying mantle.
Theory of Plate Tectonics explains the structure of the earth's crust and the changes that result from the lithospheric plates that move slowly over the underlying mantle.

7. EXAMPLES OF THEORIES
Atomic theory states that all matter is made up of tiny indivisible particles.
3- Atomic theory states that all matter is made up of tiny indivisible particles.
4- Cell theory refers to the idea that cells are the basic unit of structure in every living thing.
Cell theory refers to the idea that cells are the basic unit of structure in every living thing.

8. EXAMPLES OF THEORIES
Theory of Evolution the theory that states that life on Earth gradually developed from simple to more complex organisms.
5- Theory of Evolution the theory that states that life on Earth gradually developed from simple to more complex organisms.

9. LAWS
Contrary to common understanding, scientific theories do not “graduate” to laws…
Scientific laws DESCRIBE events in nature as a fact, but are not explained as to why it happens.
Scientific laws are typically shown as a formula representing how nature will behave under certain conditions. Most theories contain laws, and explain why laws work and what they mean.
A scientific law is a fact that describes an event in nature.

10. EXAMPLES OF LAWS
The Law of Universal Gravitation is the principle that two particles attract each other with forces directly proportional to the product of their masses divided by the square of the distance between them.
1- The Law of Universal Gravitation is the principle that two particles attract each other with forces directly proportional to the product of their masses divided by the square of the distance between them.
2- The Law of Superposition states that in any sequence of sedimentary rocks which has not been disturbed, the oldest strata lie at the bottom and the youngest at the top.
The Law of Superposition states that in any sequence of sedimentary rocks which has not been disturbed, the oldest layer lie at the bottom and the youngest at the top.

11. EXAMPLES OF LAWS
The Law of Conservation of Mass is a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants.
3- The Law of Conservation of Mass is a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants.
4- The Law of Conservation of Energy states that energy cannot be created or destroyed, but it can be transferred or transformed from one form to another.
The Law of Conservation of Energy states that energy cannot be created or destroyed, but it can be transferred or transformed from one form to another.

12. Is it Repetition or Replication?
Multiple Trials
Redo entire experiment
Precision (How close are the results to each other?)
Accuracy (True value)
Meaning: To “REPEAT”
Meaning: To “REPLICATE” COPY

13. Repetition vs Replication Video Link
Note: This is a short video explaining the difference between repetition and replication. It is a reinforcement for the table that is on the previous slide.

14. Scientific Inquiry Vocabulary
Qualitative data and Quantitative data.
Qualitative data is expressed with words and quantitative data is expressed in numbers.
Repetition and Replication
Repetition refers to repeated trials within an experiment and Replication refers to doing the
entire experiment over again.
Independent variable and Dependent Variable
The independent variable is what is being tested/manipulated by the investigator. A
dependent variable is the outcome factor that we are measuring in the experiment.
Control Group and Experimental Group
The control group is the group that we are comparing our test with. The experimental group
is the group that we have changed by adding an independent variable
Scientific Theory and Scientific Law
A scientific theory explains how nature works (why it happened). A scientific law describes
what nature does. (usually with a mathematical formula)
Control and Constant
A control is the factor that is used to compare to in an experiment. The factor that the
independent variable has not been applied to. A constant is a factor that remains the same in
every part of the experiment.
Hypothesis and Conclusion
A hypothesis is a testable question based on prior knowledge, observations, and research.
A conclusion is a statement that explains the results of the experiment and states if hypothesis
has been supported or disproved.