1. Introduction to Science
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2. Discuss Do you understand each of the graphic organizers on page 4?
Which type do you like best?
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3. How Science Takes Place
Scientists perform experiments to
find a new aspect of the natural world
explain a known phenomenon
check results of other experiments
test predictions of current theories
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4. Scientists What Scientists Do investigate plan experiments Observe
always test the results
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5. Science
the knowledge obtained by observing natural events and conditions in order to discover facts and formulate laws or principles that can be verified or tested
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6. The Branches of Science
Most of the time, natural science is divided into biological science, physical science and Earth science.
biological science: the science of living things
botany, ecology
physical science: the science of matter and energy
chemistry: the science of matter and its changes
physics: the science of forces and energy
earth science: the science of the Earth, the atmosphere, and weather
geology, meteorology
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7. Science and technology work together
pure science: the continuing search for scientific knowledge
technology: the application of science for practical purposes
Advances in science and technology depend on each other.
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8. Scientific Laws and Theories
law: a descriptive statement or equation that reliably predicts events under certain conditions
theory: a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation
Theories explain why something happens, laws explain how something works.
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9. Scientific Theories Experimental results support laws and theories.
Scientific theories are always being questioned and examined. To be valid, a theory must:
explain observations
be repeatable
be predictable
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10. Qualitative vs. Quantitative
qualitative statement: describes something with words
quantitative statement: describes something with numbers or mathematical equations
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11. Models Models can represent physical events.
model: a representation of an object or event that can be studied to understand the real object or event
Scientists use conceptual, physical, and computer models to study objects and events.
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12. Discuss What are the two branches of physical science?
What are three types of models used by scientists?
Compare and contrast a scientific law and a scientific theory.
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13. Science Skills
Identifying problems, planning experiments, recording observations, and correctly reporting data are some of the most important science skills.
Scientists approach a problem by thinking logically.
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14. Critical Thinking Critical thinking helps solve problems logically.
critical thinking: the ability and willingness to assess claims critically and to make judgments on the basis of objective and supported reasons
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15. Scientific Method Scientists use scientific methods to solve problems.
scientific method: a series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions
The scientific methods are general description of scientific thinking rather than an exact path for scientists to follow.
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16. Hypothesis a possible explanation or answer that can be tested
Scientists test a hypothesis by doing a controlled experiment.
controlled experiment: an experiment in which the variables that could affect the experiment are kept constant (controlled) except for the one that you want to measure
variable: a factor that changes in an experiment in order to test a hypothesis
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17. Units of Measurement
Scientists use standard units of measure that together form the International System of Units, or SI.
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18. SI base units SI units are used for consistency.
SI has seven base units.
derived units: combinations of the base units
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19. SI (Le Système Internationale d’Unités)
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20. SI prefixes
SI prefixes are for very large and very small measurements.
The prefixes are multiples of ten.
SI prefixes for large measurements
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21. More SI prefixes SI prefixes for small measurements
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22. Common measurements Measurements quantify your observations.
length: a measure of the straight-line distance between two points
mass: a measure of the amount of matter in an object
volume: a measure of the size of a body or region in three-dimensional space
weight: a measure of the gravitational force exerted on an object
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23. Discuss When might a scientist change a hypothesis?
A student needs to measure the volume of a liquid. What tool could the student use?
Look at Figure 1 on page 14. Answer the question in the caption.
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24. Conversions Method that always works:
Write conversion factors as fractions that equal 1
Multiply by fractions created
Repeat until you get the units you want
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25. Example
Using the conversion factor 1 inch = 2.54 cm, convert 8.5 inches to cm.
Write conversion factor as fractions
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26. Conversion factor fractions both equal 1
We can multiply by them without changing the value
To decide which fraction to use, look at units of what is being converted
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27. We want inches to cancel out, so it needs to be in the denominator
Given: 8.5 inches
We want inches to cancel out, so it needs to be in the denominator
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28. Example Using the conversion factor 1 m = 100 cm, convert 3.2 m to cm.
Write conversion factor as fractions
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29. We want m to cancel out, so it needs to be in the denominator
Given: 3.2 m
We want m to cancel out, so it needs to be in the denominator
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30. SI shortcut Measurement in SI is based on multiples of 10.
To multiply or divide by multiples of 10, you just move the decimal point.
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31. Using the prefix table
Count the number of columns you move in the table.
Move the decimal point the same number of places and in the same direction
If converting from a smaller unit to a larger one (like cm to km), move the decimal to the left. (remember “ to Larger; to Left)
If converting from a larger unit to a smaller one (like kg to mg), move the decimal to the right.
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32. Example
Convert 3.2 m to cm
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33. Example
Convert 500 mg to kg
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34. You Try
Convert 5 dm to m
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35. You Try
Convert 567 cm to mm
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36. Presenting Scientific Data
Because scientists use written reports and oral presentations to share their results, organizing and presenting data are important science skills.
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37. Line graphs Line graphs are best for continuous change.
dependent variable: values depend on what happens in the experiment
Plotted on the y-axis
independent variable: values are set before the experiment takes place
Plotted on the x-axis
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38. Line Graph
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39. Bar graphs Bar graphs compare items.
A bar graph is useful for comparing similar data for several individual items or events.
A bar graph can make clearer how large or small the differences in individual values are.
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40. Bar Graph
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41. Pie graphs Pie graphs show the parts of a whole.
Composition of a Winter Jacket
Pie graphs show the parts of a whole.
A pie graph is ideal for displaying data that are parts of a whole.
Data in a pie chart is presented as a percent.
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42. Writing Numbers in Scientific Notation
To reduce the number of zeros in very big and very small numbers, you can express the values in scientific notation.
scientific notation: a method of expressing a quantity as a number multiplied by 10 to the appropriate power
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43. Writing Numbers in Scientific Notation, continued
Some powers of 10 and their decimal equivalents are shown below.
103 = 1,000
102 = 100
101 = 10
100 = 1
10-1 = 0.1
10-2 = 0.01
10-3 = 0.001
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44. Writing Scientific Notation
Example
The adult human heart pumps about 18,000 L of blood each day. Write this value in scientific notation.
1. Move the decimal point until there is one nonzero digit in front of the decimal
1.8000
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45. 2. Count how many places you moved the decimal point and note which direction you moved it.
to moved the decimal 4 places to the left
3. The number of places you moved the decimal gives you the absolute value of the exponent
moving 4 places means 1.8  104 or 1.8  10-4
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46. 3. If you move the decimal to the left, the exponent is positive
3. If you move the decimal to the left, the exponent is positive. If you moved it to the right, the exponent is negative
18,000 L can be written as 1.8  104 L
Hint:
Large numbers (more than 10) have positive exponents
Small numbers (less than 1) have negative exponents
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47. Example Write 0.0254 m in scientific notation.
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48. You try Write 6,210 km in scientific notation.
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49. Example
Write 2.71 x 10-9 kg in long form.
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50. You try
Write 6.28 x 107 m in long form.
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51. Calculations with Scientific Notation
When you use scientific notation in calculations, you follow the exponent rules.
When you multiply two values in scientific notation, you add the exponents.
When you divide, you subtract the exponents.
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52. Example
Your county plans to buy a rectangular tract of land measuring 5.36 x 103 m by 1.38 x 104 m to establish a nature preserve. What is the area of this tract in square meters?
1. List the given and unknown values.
Given: length (l )= 1.38  104 m
width (w) = 5.36  103 m
Unknown: area (A) = ? m2
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53. 2. Write the equation for area.
A = l  w
3. Insert the known values into the equation, and solve.
A = (1.38  104 m) (5.36  103 m)
Regroup the values and units as follows.
A = (1.38  5.36) (104  103) (m  m)
When multiplying, add the powers of 10.
A = (1.38  5.35) (104+3) (m  m)
A =  107 m2
A = 7.40  107 m2
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54. Accuracy and Precision
accuracy: a description of how close a measurement is to the true value of the quantity measured
precision: the exactness of a measurement
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57. Significant Figures
Scientists use significant figures to show the precision of a measured quantity.
significant figure: a prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement
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58. Using Significant Figures
Round your answers to the correct significant figures.
When you use measurements in calculations, the answer is only as precise as the least precise measurement used in the calculation.
The measurement with the fewest significant figures determines the number of significant figures that can be used in the answer.
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59. Example
Calculate the volume of a room that is m high, 4.25 m wide, and 5.75 m long. Write the answer with the correct number of significant figures.
1. List the given and unknown values.
Given: length, l = 5.75 m
width, w = 4.25 m
height, h = m
Unknown: volume, V = ? m3
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60. 2. Write the equation for volume.
V = l  w  h
3. Insert the known values into the equation, and solve.
V = 5.75 m  4.25 m  m
V = m3
The answer should have three significant figures, because the value with the smallest number of significant figures has three significant figures.
V = 76.4 m3
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61. Example
Perform the following calculation and write the answer with the correct number of significant figures.
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62. You try
Perform the following calculation and write the answer with the correct number of significant figures.
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