Presentation on theme: "Big Idea 3: The Role of Theories, Laws, Hypotheses, and Models"— Presentation transcript:
1 Big Idea 3: The Role of Theories, Laws, Hypotheses, and Models Description The terms that describe examples of scientific knowledge, (e.g. "theory," "law," "hypothesis," and "model“) have very specific meanings and functions within science.
2 Benchmark Number & Descriptor SC.7.N.3.1Recognize and explain the difference between theories and laws, and give several examples of scientific theories and the evidence that supports them.SC.7.N.3.2Identify the benefits and limitations of the use of scientific models.
3 SCIENTIFIC THEORYA scientific explanation to a pattern in the natural worldMany observations and much evidence is needed in order to create a valid theory.Scientific investigation is a key part when creating theories.Theories may be supported by scientific evidence at the time but may be incorrect.Evidence may change with time; better technologyExample: Geocentric (earth in middle of solar system) to Heliocentric model (sun in middle of solar system)
4 EXAMPLES of SCIENTIFIC THEORIES Big Bang TheoryThe universe has expanded from hot, dense, gaseous conditions.Tectonic Plate TheoryThe surface of the earth is composed of tectonic plates, which move slowly.Atomic TheoryAll matter is made up of atoms.Theory of Matter and EnergyMatter and Energy are always conserved.Cell TheoryCells form the foundation, the basic unit of all living organisms.Theory of EvolutionAll life on earth evolved from simple forms.
5 SCIENTIFIC LAWThis is a statement of fact meant to describe, in concise terms, an action or set of actions. It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don’t really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true.Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.Some scientific laws, or laws of nature, include the law of gravity, Newton's laws of motion, the laws of thermodynamics, Boyle's law of gases, the law of conservation of mass and energy, and Hook’s law of elasticity.
6 EXAMPLES of SCIENTIFIC LAWS Ohm’s LawI = V/RRelationship between current, voltage, and resistanceNamed after Georg OhmNewton’s Law sObjects at rest/motion stay at rest/motion until a force acts on it.Objects will accelerate in the direction of the force (F = M*A).Action-Reaction forces (equal and opposite)Law of SegregationFor any pair of characteristics there is only one gene in a gamete even though there are two genes in ordinary cells.Founder – Gregor MendelIdeal Gas LawCombination of Charles's and Boyle’s gas laws.Formula: pV = nRTRelates pressure, temperature, and volume of gassesFor additional laws see this website:
7 KNOWLEDGE CHECKWhat is the difference between a scientific theory and a scientific law?Can a scientific theory change over time? Why?List 2 examples of scientific theory and scientific law.
8 KNOWLEDGE CHECKWhat is the difference between a scientific theory and a scientific law? Laws are generalizations about what has happened; Theories are explanations of observations (or of laws).Can a scientific theory change over time? Why? Yes, as technology progresses, new evidence can be discovered helping to justify or falsify a theory.List 2 examples of scientific theory and scientific law. Theory: Atomic theory, Big Bang theory; Law: Newton’s Laws, Law of Segregation
10 MODELSModels are a visual representation that help scientists study something in more depth.There are 2 general types of models:PhysicalModels that you can touchRepresentation of an item they want to studyMathematicalMade up of math equations and dataThey allow you to calculate things.
11 MODELS BENEFITS LIMITATIONS Models can be used for the following: Study objects that are too small to seeStudy objects that are too large to seeHelp explain the past and the presentHelp predict the futureScientists must realize the limitations of models, especially when reading the information obtained by them.Because we may not see an actual picture, models are thoughts and ideas from our heads.Some calculations are very complex, and computers are needed to find the answer.
12 KNOWLEDGE CHECK Why do scientists use models? Describe the two main types of scientific models.List 2 benefits of using models.List 2 limitations when using models.
13 KNOWLEDGE CHECKWhy do scientists use models? To help create a visual representation when studying something in more depth.Describe the two main types of scientific models. Physical – Hands on model; Mathematical – equation providing dataList 2 benefits of using models. To help explain the past and the present, study objects that are too small/large to seeList 2 limitations when using models. Some physical models are subjective since they are based on theories/observations; since some theories need computers to solve them, scientists must be able to read and interpret the data.