Transcript Nature Of Science - OnCourse Systems

Nature Of Science
Lesson 2 Measurement and Scientific Tools
Pages: NOS 12 to NOS 18
Essential Questions:
Copy into you binder
Pages NOS 12 to NOS 18
Lesson 2 Measurement and Scientific Tools
Essential Questions:
 What is the difference between accuracy and
precision?
 Why should you use significant digits?
 What are some tools used by Life Scientists?
Description and Explanation
 A description is a spoken or written summary of
observations.
 Two types of descriptions:
 Qualitative – uses your senses (sight, sound, touch, smell, and
taste) to describe in words what you observe.
 Quantitative – uses numbers to describe the observation.
 An explanation is an interpretation of your
observations.
 When you explain something, you try to interpret
your observations, which can lead to a
hypothesis
The International System Of
Units
 The International System of Units (SI) is an
internationally accepted system for measurement.
 All SI units are derived
from seven base units.
The International System of
Units (cont.)
 A prefix can be added to a
base unit’s name to indicate
either a fraction or a multiple
of that base unit.
 Prefixes are based on powers
of ten, such as 0.01 and 100.
 Powers of 10 Video (9 min)
http://teachertube.com/viewVideo.php?video_id=
119236
Brain Pop
 Metric Units
 http://www.brainpop.com/science/scientificinquiry/
metricunits/preview.weml
Reading Check Question
 What is SI?
 SI is an accepted international system for
measurement.
 How does having an international system of units
help scientists communicate worldwide?
 They all use the same type of measurements, which
makes sharing scientific information easier.
Accuracy and Precision
 Accuracy is a description of how close a
measurement is to an accepted or true value.
 Precision is a description of how similar or close
measurements are to each other.
Example: Difference between
precise and accurate
 The data taken by student A are more accurate because
each value is close to the accepted value. The data
taken by student C are more precise because the data
are similar. The data taken by student B are neither
precise nor accurate because they are very different
from each other and not close to the accepted value.
Brain Pop
 Precision and Accuracy
 http://www.brainpop.com/science/scientificinquiry/p
recisionandaccuracy/preview.weml
Measurement and Accuracy
 All measurements have some uncertainty.
 The tools used to make measurements limit the
accuracy of the measurements.
 Example: If you were to use a thermometer whose
measurements are divided into whole numbers to
measure the temperature at which sugar melts and your
measurements were between 183oC and 184oC your
temperature would be an estimate between these two
numbers. If you were to measure the temperature at
which sugar melts and were using a thermometer whose
numbers are divided into tenths and your measurements
were between 183.2oC and 183.3oC you would be able
to get a more accurate estimate.
Reading Check Question
 How can you tell the data taken by Student C
shown in Table 4 is precise?
 The data points are consistently the same value.
 How do accuracy and precision differ?
 Accuracy indicates how close a measurement is to
an accepted value, while precision is how close
measurements are to each other.
Significant Digits
 Significant digits are
the number of digits in
a measurement that
are known with a
certain degree of
reliability.
 The significant digits in
a measurement include
all digits you know for
certain plus one
estimated digit.
Significant Digits
(cont.)
 Using significant digits lets others know how certain
your measurements are.
0.05
Math Practice – Significant
Digits
Copy the following table into your notebook
and complete columns 2 and 3
Example
4.01
2.02
0.0057
1,500
0.500
Significant Digits
Applied Rules
Scientific Tools
 Science journals are for
recording descriptions,
explanations, plans, and
steps used in a scientific
inquiry.
 A science journal can be
a loose-leaf binder, a
spiral notebook, or a
marble notebook.
Scientific Tools
(cont.)
 A triple-beam balance or digital balance is used
by scientists to measure mass.
Scientific Tools
 A thermometer
measures the
temperatures of
substances.
 We always use Degrees
Celsius (oC) in the
science classroom.
(cont.)
Scientific Tools
 Flasks, beakers,
petri dishes, test
tubes, and
specimen jars are
used as containers.
(cont.)
Scientific Tools
 Graduated cylinders are used
to measure the volume of a
liquid.
 The unit of measure for the
volume of a liquid is the liter (L)
or milliliter (mL)
(cont.)
Scientific Tools
(cont.)
 Microscopes, such as dissecting microscopes and
compound light microscopes, enable you to
observe small objects that you cannot observe with
just your eyes.
Scientific Tools
 Scientists use
computers to
compile, retrieve,
and analyze data for
reports.
(cont.)
Tools Used by Life Scientists
 A magnifying lens is a handheld lens that magnifies, or
enlarges, an image of an
object.
 To observe items using a
compound light microscope,
you must place it on a thin,
rectangular piece of glass
called a slide.
Tools Used by Life Scientists
 Scientists use dissecting
tools, such as scalpels
and scissors, to examine
tissues, organs, or
prepared organisms.
 A pipette or eyedropper
is a small glass or plastic
tube used to draw up and
transfer liquids.
(cont.)