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Explore the world around us through the lens of science. This article discusses the definition of science, how scientists work, and the scientific method. Learn about various types of investigations and the importance of observations and hypotheses.
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What is Science? (1-1) The root sci- means “to know”. Science is one way of investigating the world in which we live. Science strives to: • explore and understand the natural world, • explain events in the natural world, and • use those explanations to make useful predictions. • Are some things unpredictable?
Things that are not science include things like… • Art • Religion • Literature • Opinion
Science can only concern itself with testable things and\or observable things
Is scientific knowledge a set truth? • No! • In our scientific explanations, we explain how things work using the knowledge we have to explain natural phenomena • When our knowledge base changes, our explanation may change
What is Science? Scientists use observations based on facts to gather data. They also use known data to make inferences (a logical interpretation of the data based on past experiences).
Determine in the picture if it is an observation (O) or an inference (I) O • _____ There are 2 doors. • _____ The people are fighting because someone ate their cookies. • _____ One door is closed. • _____ They are hitting each other hard. • _____ Glass is broken. I O I O
How Scientists Work • “The” Scientific MethodScientists solve problems, but the method may vary based on the problemThe three types of investigations: • Experimental Research Design • Correlation • Investigation
Descriptive Investigations - involves describing and/or quantifying parts of a natural system • Comparative Investigations - involves collecting data on different populations/organisms, or under different conditions (e.g. time of year, locations, temperature), to make a comparison • Experimental Investigations - involves a process in which a "fair test" is designed in which variables are manipulated, controlled and measured in an effort to gather evidence to support/refute a relationship
Steps to Experimental Scientific Investigation (The Scientific Method): • 1. Observe – make an observation of the world around you. There are two kinds of observations: • Qualitative observation – descriptive observation • Ex: The plant is green. • Quantitative observation – a numerical observation. • Ex: The flask contains 12.45 ml. There are 4 pennies.
Determine if the statement is qualitative (A) or quantitative (B). A • _____ The sky is blue. • _____ There are 4 clouds. • _____ There are 3 hills. • _____ The first hill is small. • _____ The clouds are small. • _____ There are a total of 38 birds. B B A A B
2. Ask a question – based on your observation, ask a question to investigate. • Ex. Redi asked the question “How do new living things, or organisms, come into being?” • 3. Research - Look in books, journals and the internet to make additional observations and research about the questions you made from your observation.
4. Formulate a hypothesis: - Propose a scientific explanation to the question being observed and researched. The statement must be testable. (“Which is best?” does not lend itself to being tested). At the end of the investigation, you will either accept or reject your hypothesis. • Ex. If meat is left uncovered, then flies will leave eggs on the meat, creating maggots.
5. Perform a controlled experiment - Develop and use the experimental design to test your hypothesis. Whenever possible, the hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled. Testing fertilizers on plant growth? Keep all other factors constant!
Variables: Factor being tested • Controlled- Variables that are kept constant • Independent- Variable being manipulated (in a graph found on the x-axis or the horizontal axis) • Dependent- Variable that responds (in a graph found on the y-axis or the vertical axis) • Control Group – the group where the independent variable is NOT applied. Meaning, nothing is changed. Used for comparison.
A way to remember variables Dependent Responding Y- axis Manipulated Independent X - axis
Repeat your experiment! • The more times you do it, the more accurate your data and results will be!!
6. Observe again - Collect data (measurements) and perform analysis on the data using graphs and charts
7. Draw conclusions - State whether or not the evidence supports the hypothesis based on your data and analysis. • Please notice that we do not prove hypotheses! Proof exists when the chance for error is 0. There is always some chance for error (no matter how small it is) and this existence of chance error means we cannot prove anything in true, honest, science.
8. Report back to the community – Experiments’ results can be used by other to help them with their own experiments. This is what keeps science progressing.
What is the difference between a hypothesis, a theory, and a law? • A hypothesis is a possible explanation for a set of observations. It has not yet been thoroughly tested.
What is the difference between a hypothesis, a theory, and a law? • A theory is a well tested explanation that unifies a broad range of observations. • A theory explains observations simply and clearly, and predictions can be made from them. • It is widely accepted by the scientific community. Theory of Plate Tectonics
What is the difference between a hypothesis, a theory, and a law? • A law is a summary of observed natural events: they are less comprehensive than theories and normally are associated with a mathematical expression. It is also widely accepted by the scientific community. Law of Universal Gravitation
Tools and Procedures Biologists use metric measurement (the SI system) to gather and interpret data. SI is the universal measurement system.
The metric system is universal measurement system based on the number 10. The meter is the distance value, the gram is the mass value, and the liter is the volume value. Conversions
Graphing- how a scientists shows patterns in data collected. • There are several kinds of graphs; not all of them are useful for data communication. Which type of graph is appropriate for which situations?
Line Graph • Line graph - compares two things in which items on one axis affect the items on the other axis. If you are comparing anything to time, it is usually a line graph. • (Ex. Amount of CO2 in the atmosphere over the last 6 decades)
Bar graph - compares two or more values. (Ex. Number of students with red hair in each class)
Pie Chart- effective in showing proportions or percentages of a whole thing. (Ex. Comparing the percentage vote that each candidate received in the election)
Graphing • Always draw lines with a ruler, use pencil, and use map pencils when necessary. Make sure your graph contains all components: • Title – tell what you are comparing or displaying (be descriptive). • X-axis – label and give scale. • Y-axis – label and give scale. • Key – give meanings of the symbols and colors used on the graph. • Data points – clearly marked, and label them if you do not have grid lines.
1) Light microscope – produces magnified images by focusing visible light rays. This microscope can be used to magnify up to 1000 times
2) Electron microscope – produce magnified images by focusing beams of electrons. This kind is used to magnify tens and hundreds of thousands of times for extremely small object like a virus. The hair on the leg of a fly(magnified by a factor of 1000) Salt crystals on the antennas of an insect(magnified by a factor of 5000)
