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1 What is Science?
Contents
Objects
and Properties
Quantifying
Properties
Measurement
Systems
Standard
Units for the Metric System
Length
Mass
Time
Metric
Prefixes
Understandings
from Measurements
Data
Ratios and Generalizations
The Density Ratio
Symbols and Equations
The
Nature of Science
The Scientific Method
Explanations and Investigations
Scientific Laws
Models and Theories
Science,
Nonscience, and Pseudoscience
From Experimentation to Application
Science and Nonscience
Pseudoscience
Limitations of Science
Overview
Students
begin by considering their immediate environment, and then logically proceed to
an understanding that science is a simple, clear, and precise reasoning and a
way of thinking about their environment in a quantitative way. Within the chapter, understandings about
measurement, ratios, proportions, and equations are developed as the student
learns the meaning of significant science words such as “theory,” “law,” and “data.” The chapter
develops a concept of the nature of scientific inquiry and presents science as
a process. It distinguishes science from
nonscientific approaches. It also
identifies pseudoscience as a distortion of the scientific process.
Suggestions
1. To
begin the discussion ask the class their definition of science, accepting all
answers. Consider the natural sciences
as the study of matter and energy in living and nonliving systems, applied
sciences (engineering), and social sciences in the discussion.
2.
When discussing the meaning of concept,
point out that different levels of thinking exist.
Lower levels are not necessarily incorrect but are incomplete compared to higher levels.
For example, a young child considers a “dog” to be the short brown furry animal that
lives across the street. Later, the child learns that a dog can be any size (within limits)
with highly variable colors, and in fact, dogs come in many sizes, colors, and patterns of
colors. Still later, a dog (Canis familiaris) is understood to be a domestic mammal
closely related to other animals (the common wolf). Each of these generalizations
represents a concept, but at different levels of understanding. This discussion of levels
of conceptualization will be useful later as a comparison when students argue a concept
of something from a lower level of understanding. Many nonscience students have an
understanding of acceleration, for example, as a simple straight-line increase in velocity.
This concept is not incorrect (the dog across the street), but it represents an incomplete
level of conceptual understanding.
3. To introduce properties and referents, display an unusual rock (not pyrite) or object and ask the class to describe it as if talking to someone on the telephone. Keep track of the descriptive terms, then list them all together and ask the students if they could visualize the object if they heard this description over the telephone. The point about typical, vague everyday communications will be obvious. Ask for a volunteer who is majoring in education (or some other major requiring communications) and who loves coffee to describe the taste of coffee to someone who has never tasted it. The student will have difficulty because of the lack of a referent. The concept of a referent will probably be new to most nonscience students, but it is an important concept that will prove useful to them throughout the course.
Lower levels are not necessarily incorrect but are incomplete compared to higher levels.
For example, a young child considers a “dog” to be the short brown furry animal that
lives across the street. Later, the child learns that a dog can be any size (within limits)
with highly variable colors, and in fact, dogs come in many sizes, colors, and patterns of
colors. Still later, a dog (Canis familiaris) is understood to be a domestic mammal
closely related to other animals (the common wolf). Each of these generalizations
represents a concept, but at different levels of understanding. This discussion of levels
of conceptualization will be useful later as a comparison when students argue a concept
of something from a lower level of understanding. Many nonscience students have an
understanding of acceleration, for example, as a simple straight-line increase in velocity.
This concept is not incorrect (the dog across the street), but it represents an incomplete
level of conceptual understanding.
3. To introduce properties and referents, display an unusual rock (not pyrite) or object and ask the class to describe it as if talking to someone on the telephone. Keep track of the descriptive terms, then list them all together and ask the students if they could visualize the object if they heard this description over the telephone. The point about typical, vague everyday communications will be obvious. Ask for a volunteer who is majoring in education (or some other major requiring communications) and who loves coffee to describe the taste of coffee to someone who has never tasted it. The student will have difficulty because of the lack of a referent. The concept of a referent will probably be new to most nonscience students, but it is an important concept that will prove useful to them throughout the course.
4.
Many devices are available from scientific equipment companies to
demonstrate the metric system of
measurement, such as the plastic liter case.
It is often useful to call attention
to the similarities between the metric prefixes and the monetary system (deci- and dime, centi- and cent, and so
forth). If students can make change,
they can use the metric system.
5. In
developing the concept of a ratio, it is useful to have a set of large blocks
that you can actually measure to
find the surface area to volume ratio.
Show all calculations on an overhead
transparency or chalkboard.
6. The
development of the concepts of a proportionality statement, an equation, and
the meaning and uses of
symbols is critical if you plan to use a problem-solving approach. The
three classes of equations provide an important mental framework on which
future concepts will be
hung. A student who does not
“understand” density has less of a problem
learning that density is a ratio that describes a property of matter. Likewise, a student
who does not “understand” an electric field has less of a problem learning that
an electric field is a concept that
is defined by the relationships of an equation.
Identifying equations
throughout the course as “property,” “concept,” or “relationship” equations will help students sort out their
understandings in a meaningful way.
7. In
the discussion of scientific laws, analysis of everyday “laws” can be useful
(as well as interesting and
humorous). One statement of Murphy’s
law, for example, is that “the bread
always lands butter side down.” Ask the
class what quantities are involved in this law
and what the relationship is. Another
everyday law is Bombeck’s law: “ugly
rugs never wear out.” You could also make up a law — [your name]’s
law: “the life span of a house plant is inversely proportional to
its cost.” Analysis?
For
Class Discussions
1. A beverage glass is filled to the brim with
ice-cold water and ice cubes floating in the water, some floating above the
water level. When the ice melts, the
water in the glass will
a.
spill over the brim.
b.
stay at the same level.
c.
be less than before the ice melted.
2. A homeowner wishes to fence in part of the
yard with a roll of wire fencing material.
If all the roll of material is used in all situations, which shape of
fenced-in yard would enclose the greatest area?
a.
square
b.
rectangle
c.
both would have equal areas.
3. Again considering the homeowner and a fence
made with a roll of wire fencing material.
If all the roll of material is used in all situations, which shape of
fenced-in yard would enclose the greatest area?
a.
right-angle triangle
b.
rectangle
c.
the answer will vary with the shape used.
4.
Which of the following is usually measured by a ratio?
a.
The speed of a car.
b.
The density of a rock.
c.
Both speed and density are ratios.
d.
Nothing is measured with a ratio.
5. A 1
cm3 piece is removed from a very large lump of
modeling clay with a volume of over 100,000
cm3.
Which piece has the greatest density?
a.
The small piece.
b.
The large piece.
c. Both the large and the small piece have the
same density.
6. The
nature of science is such that
a.
when proven, scientific theories become scientific laws.
b.
nature behaves as it does because of scientific laws.
c.
neither of these statements are true.
7. Which of the following statements is most
correct?
a.
Science is always right.
b.
Nonscientific study has little value.
c.
Science has all the answers.
d.
Science seeks to explain natural occurrences.
8. When a scientist sees patterns or
relationships among a number of isolated facts,
a.
laws or principles are developed.
b.
truth has been reached.
c.
elaborate tests must be developed to prove the pattern exists.
d.
as a rule, the pattern must be published.
9.
Scientific method involves each of the following except
a.
systematic search for information.
b.
observation and experimentation.
c.
forming and testing possible solutions.
d.
formulation of laws and principles that control the observed facts.
10. Select the description of a controlled
experiment:
a.
Group I, 50 mice fed, watered, Group II, 25 mice differently fed,
watered.
b.
Group I, 25 mice fed, watered, Group II, 50 mice 1/2 fed, watered.
c.
Group A, 50 mice fed, watered, Group B, 50 mice fed differently, watered
differently.
d.
Group A, 50 mice fed, watered, Group B, 50 mice fed different food,
watered.
Answers: 1b (ice floats above the water line because
it is less dense; when it melts it occupies the same volume displaced while
floating), 2a, 3c, 4c, 5c, 6c, 7d, 8a, 9d, 10d.
Answers
to Questions for Thought
1. A
concept is a generalized mental image of an object or idea.
2. A measurement statement always contains a number and the name of the referent unit.
The number tells “how many,” and the unit explains “of what.”
3. The primary advantage of the English system of measurement is that mostUnited States
citizens are familiar with the basic units and their sizes. The metric system has the
advantage of easily converting the units to a convenient size merely by moving the
decimal and using the appropriate prefix with the basic unit.
4. The meter is the metric standard of length and is defined as the distance light travels in a
vacuum in 1/299,792,458 seconds. The metric standard of mass is the kilogram, which
is defined as the mass of a standard kilogram kept by the International Bureau of
Weights and Measures inFrance
defined as the time required for a certain number of vibrations to occur in a type of
cesium atom.
5. The density of a liquid does not depend upon the shape of its container. Density is a
ratio of mass per unit volume. As long as this ratio stays the same the density does not
change.
6. A flattened pancake of clay has the same density as a ball of the same clay. Even though
the shape of the material has changed, the volume and the mass of the material have not
changed. Since density is a ratio of mass per unit volume the density is the same.
2. A measurement statement always contains a number and the name of the referent unit.
The number tells “how many,” and the unit explains “of what.”
3. The primary advantage of the English system of measurement is that most
citizens are familiar with the basic units and their sizes. The metric system has the
advantage of easily converting the units to a convenient size merely by moving the
decimal and using the appropriate prefix with the basic unit.
4. The meter is the metric standard of length and is defined as the distance light travels in a
vacuum in 1/299,792,458 seconds. The metric standard of mass is the kilogram, which
is defined as the mass of a standard kilogram kept by the International Bureau of
Weights and Measures in
defined as the time required for a certain number of vibrations to occur in a type of
cesium atom.
5. The density of a liquid does not depend upon the shape of its container. Density is a
ratio of mass per unit volume. As long as this ratio stays the same the density does not
change.
6. A flattened pancake of clay has the same density as a ball of the same clay. Even though
the shape of the material has changed, the volume and the mass of the material have not
changed. Since density is a ratio of mass per unit volume the density is the same.
7. A
hypothesis and a scientific theory are alike in that both are working
explanations. A hypothesis, however, usually deals with a narrow range of
phenomena, while a theory is a broad working hypothesis that forms the basis
for thought and experimentation in a field of science.
8. A
model is a mental or physical representation of something that cannot be
directly
observed. A simpler representation of a complex phenomenon is also a model. A model
is used as an easily visualized and understood analogy to some behavior or system that is
not directly observable or is very complex.
9. Theories do not always enjoy complete acceptance but are rarely rejected completely.
The better a theory explains the results of experiments and correctly predicts the results
of new experiments, the greater the degree of acceptance. Theories that do not conform
with experiments are usually modified and gain wider acceptance.
observed. A simpler representation of a complex phenomenon is also a model. A model
is used as an easily visualized and understood analogy to some behavior or system that is
not directly observable or is very complex.
9. Theories do not always enjoy complete acceptance but are rarely rejected completely.
The better a theory explains the results of experiments and correctly predicts the results
of new experiments, the greater the degree of acceptance. Theories that do not conform
with experiments are usually modified and gain wider acceptance.
10. Pseudoscience is a
methodology, presentation, or activity that appears to be or is presented as
being scientific, but is not supportable as valid or reliable. It can be identified by the following
characteristics: a lack of valid substantiation of claims, untestable
hypotheses, unwillingness to submit to rigorous testing, or inability to repeat
the experiments.
Group
B Solutions
1.
Answers will vary. In general,
mass and weight are proportional in a given location, so
1 kg µ 2.21 lb
Kilograms can be converted to grams by
the procedure described in the appendix A of
the text.
the text.
1.00 kg =
1000.0 g
2.
Since density is given by the
relationship r = m/V, then
3. The volume of a sample of
copper is given and the problem asks for the mass. From the
relationship of r = m/V, solving for the mass (m) tells you that the density (r)
times the volume (V) gives you the mass, m = rV. The density of copper, 8.96 g/cm3, is
obtained from table 1.3 in the text, and
relationship of r = m/V, solving for the mass (m) tells you that the density (r)
times the volume (V) gives you the mass, m = rV. The density of copper, 8.96 g/cm3, is
obtained from table 1.3 in the text, and
4.
Solving the relationship r =
m/V
for volume gives V = m/r,
and
The answer is rounded up to provide two
significant figures, the least number given in
the density of 0.92 g/cm3. This assumes that 5,000 grams of ice means exactly 5,000
grams, that is, that 5,000 has four significant figures.
the density of 0.92 g/cm3. This assumes that 5,000 grams of ice means exactly 5,000
grams, that is, that 5,000 has four significant figures.
5. A
50.0 cm3 sample with a mass of 51.5 grams has a density
of
According to table 1.3, 1.03 g/cm3 is the mass density of seawater, so the
substance must
be seawater.
be seawater.
6. The
problem asks for a mass, gives the mass density of gasoline, and gives the
volume.
Thus, you need the relationship between mass, volume, and mass density. The volume
is given in liters (L), which should first be converted to cm3 because this is the unit in
which density is expressed. The relationship of r = m/V solved for mass is rV, so the
solution is
Thus, you need the relationship between mass, volume, and mass density. The volume
is given in liters (L), which should first be converted to cm3 because this is the unit in
which density is expressed. The relationship of r = m/V solved for mass is rV, so the
solution is
The answer is rounded up to provide three
significant figures, the number of significant
figures given in the density and volume measurements. The answer of 64,300 g is
correct, but usually it is better to express the answer using “standard” conventions being
used. Using scientific notation would be better yet because of ease of showing
significant figures and the ease of performing mathematical operations.
figures given in the density and volume measurements. The answer of 64,300 g is
correct, but usually it is better to express the answer using “standard” conventions being
used. Using scientific notation would be better yet because of ease of showing
significant figures and the ease of performing mathematical operations.
7.
From table 1.3, the density of iron is given as 7.87 g/cm3.
Converting 2.00 kg to
the same units as the density gives 2,000 g. Solving r = m/V for volume gives
the same units as the density gives 2,000 g. Solving r = m/V for volume gives
8. The
length of one side of the box is 1.00 m.
Reasoning: Since the density of
water is
1.00 g/cm3, then the volume of 1,000,000 g (1,000 kg) of water is 1,000,000 cm3. A
cubic box with a volume of 1,000,000 cm3 is 100 cm (since 100 ´ 100 ´ 100 =
1,000,000). Converting 100 cm to m units, the cube is 1.00 m on each edge.
1.00 g/cm3, then the volume of 1,000,000 g (1,000 kg) of water is 1,000,000 cm3. A
cubic box with a volume of 1,000,000 cm3 is 100 cm (since 100 ´ 100 ´ 100 =
1,000,000). Converting 100 cm to m units, the cube is 1.00 m on each edge.
9. The
relationship between mass, volume, and density is r = m/V. The problem gives a
volume, but not a mass. The mass, however, can be assumed to remain constant during
the compression of the bun so the mass can be obtained from the original volume and
density, or
volume, but not a mass. The mass, however, can be assumed to remain constant during
the compression of the bun so the mass can be obtained from the original volume and
density, or
A mass of 36 g and the new volume of 195
cm3 mean that the new density of the
crushed bread is
crushed bread is
10. According to table 1.3, lead has a density of
11.4 g/cm3. Therefore a 1.00 cm3 sample of
lead would have a mass of
lead would have a mass of
Also according to table 1.3, iron has a
density of 7.87 g/cm3. To balance a mass of
11.4 g of lead, a volume of this much iron would be required:
11.4 g of lead, a volume of this much iron would be required:
For
Further Analysis
- Answering this
question requires the critical thinking skills of clarifying values and
developing criteria for evaluation. Answers will vary.
- This question
requires students to explore beliefs and evaluate arguments. Answers will
vary.
- This requires the
student to evaluate a concept, comparing the concept with the real world.
The evaluation should note that density is a mass over volume ratio and
larger and larger volumes with the same mass reduces the density.
- Thinking
precisely, the student will realize that doubling a quantity that is
squared will result in a four-fold increase.
- Thinking
precisely and evaluating critical vocabulary is required. Answers will
vary.
- Thinking precisely and evaluating
critical vocabulary is required. Answers will vary.
- Exploring
arguments and clarifying issues is required. Answers will vary.
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