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Science - Grade Nine

Fundamental Concepts:

Science is the body of knowledge that explains the nature of matter, and how energy and matter interact.
Technology  uses scientific discoveries to invent devices and processes to advance the progress of society.
Technology is applied Science.

Matter is all that is around us.  Mater is what the universe is made of. A definition of matter could be "anything that has mass and occupies volume".

Mass is the amount of substance in an object.  Volume is the amount of space an object takes up.

Learn how to properly read a graduated cylinder and a balance. (Follow the links)

Scientists try to explain phenomena, discover new things, and solve problems using the Scientific Method.
The Scientific Method is a process of discovery which makes use of several important steps.

The steps of the Scientific Method of discovery are:

  1. Identify the problem

  2. Collect information about the problem

  3. form a hypothesis about the causes of the problem

  4. perform experiments to arrive at a conclusion as to the causes of the problem

  5. analyze the data collected during the experiment

  6. draw conclusions based on the data collected.

Conclusions and hypothesis to experiments can take several different forms

  1. Law -- an indisputable scientific proof or truth that can be verified over and over again
    Example: Newton's Laws of Motion
  2. Theory -- A consistent explanation to observations that can be supported in laboratory experiments
    but that could, at some future point,  be proven wrong through more experiments.
    Example: The Cell Theory
  3. Model -- A probable explanation of the causes of a problem at its early stages of inception.
    Example: The model of the Hydrogen Atom

A Hypothesis is an educated guess that scientists make regarding the solution to a problem or its causes.

During an experiment scientists make many observations.
In general,  Observations can be grouped as one of two possible categories:

Measuring, investigating,  and observing involves the use of variables.

Variables are measurable factors or quantities taken during the course on an experiment.

There can be two types of variables:

Dependent variables are measurable quantities that are influenced by other factors during an experiment.

Independent variables are measurable quantities that are not influenced by other factors during an experiment.

Example:

You are heating water in a beaker for 5 min and recording the temperature of the water every 30 s.

In this experiment, temperature is the dependent variable and time is the independent variable.  Time is not affected by temperature.
Temperature, on the other hand, increases as time goes on.

 

 The International System of Units (SI) is used in modern day scientific experiments

These are some base units and the quantity they measure in the metric system.

                1.  Length -- meter (m)  
                2.  Mass -- kilogram (kg)
                3.  Time -- second (s)
                4.  Temperature -- Kelvin (K)
                5.  Amount of Substance -- mole (mol)
                6.  Electric Current -- ampere (A)
                7.  Light Intensity -- candela (cd)

 Prefixes are small "words" placed in front of units to indicate a multiple factor of ten of a unit.
The basic metric prefixes used in science are

                 1.  mega-  M            2.  kilo-  k              3.  hecto-  h                4.  deca-  da           
                 5.  deci-  d              6.  centi-  c              7.  milli-  m             8.  micro- 

In the  SI System of Measurement we have some basic orthographic rules .  These rules tell us the proper way of writing 
quantities and units in the Metric system. 

                 1.  75 cm (not 75cm) --  leave a space between the last digit and the unit.

                2.  1.36 m (not 1.36 m.)  --  don't put a period after the unit unless it is at the end of the sentence

                3.  6 m (not 6 meters);  six meters (not six m)  --  use numbers and symbols together only!!

                4.  0.25 cm (not 1/4 cm)  --  use decimal fractions instead of fractions

                5.  0.67 mm (not .67 mm)  --  put a zero in front of a decimal if the number is less than 1

 Accuracy, Precision, and Errors

Experiments are not perfect.  Scientists expect imperfections and errors due to the limitations of their experimental techniques,
 equipment and other circumstances.  Inaccuracy, error, and precision in scientific experiments can be summarized as follows.

            Accuracy:                how close is the measurement to its real value
             Error:                the difference between the observed value and the real value
             Precision:                how close are two observed measurements from each other that are made in the same way

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