H.S. Physical ScienceChapters 1 and 2

Chemistry – How all forms of matter interact with each other, and the changes that can occur (physical or chemical changes). Examples: ice tea or table salt.

Physics – How energy affects matter. Examples of this energy includes motion, force, gravity, electricity, light and heat.

Physical Science tries to answer the questions what and how (not why ).

1. Cannot make value judgments (Good vs Bad)

2. Cannot prove a universal negative (“There is no such thing as….”)

3. It is as limited as our instruments.

Scientific Statements

1. Facts – observable and indisputable.

2. Data – information gained from experimentation.

Technology is the application of knowledge, tools, and materials to solve problems and accomplish tasks. Examples can range from a pencil, to a beaker, to a computer.

In technology we often use small objects (pencils) to large objects (computers) in order to gain knowledge about the outside world (science).

Models are visual representatives of an object or system (model airplane or rocket, the solar system, cells, etc.).

Objects as models – example, using a slinky to demonstrate sound waves

Models can be used to test hypotheses (From Earth to the Moon) or illustrate theories (atomic theory).

Models can be used to save time and money before the actual object is created.

A hypothesis is a belief, based on research and observations, that can be proven or disproven by a series of investigations (experiments.)

A theory is an explanation of things/events that is based on many observations and repeated investigations. Theories may change over time (heat is a liquid?)

A scientific law is consistently true (what will happen under certain conditions.) The law of gravity is an example.

A system is a collection of structures that relate to one another

In science we use a systematic way to apply knowledge to a new problem. Critical thinking is the ability to use knowledge to decide if you agree with an explanation.

An inference is an explanation of what is observed to help scientists modify an experiment.

The scientific method is a series of steps used to answer questions and solve problems.

Everyone uses the scientific method in one form or another.

1. Identify the problem (in the form of a

question).

2. Gather information by research.

3. Form a hypothesis (see definition).

4. Experimentation (at least 3 times with

consistent results.)

5. Analyze data & make conclusions.

6. Make predictions.

- An experiment is a controlled test. This means that all aspects of the experiment is under the control of the scientist.

- The variables in an experiment are the items that can affect the experiment (and produce data.)

- For accuracy in proving/disproving a hypothesis, only ONE variable can be tested at a time. The rest of the varibles must remain constant. This variable is called the INDEPENDENT VARIABLE.

- The results achieved, based on the manipulation of the independent variable, is called the DEPENDENT VARIABLE.

If you are in the high school physical science course (but you are not in the high school credited math class), then you are required to complete a science fair project during the fall semester (information to come.)

It is very important that you know and apply the following information on the Scientific Method to your project.

Step 1: Does the Amount of Sunlight Affect the Growth of an African Violet?What variable is being tested? (This is your independent variable)What are other variables that need to remain constant

throughout the experiment? (what else is needed for African Violets to grow?)

Step 2: Gather Information. What research would you need to do before you

begin your experiment?

Consider and research at least 3 areas involved in your question.

Step 3: Form a hypothesis.Base the hypothesis strictly on the research. The hypothesis is a statement made in the third person. Example:

Based upon research indicating that African Violets thrive in well-lit

areas, this scientist believes that the

provision of extra sunlight will enhance the growth of the plant.

Step 4: Experimentation – You must collect MEASURABLE DATA!

Remember, - You can only test the amount of sunlight (everything else

must be constant.)- You must test at least 3 times (or more) until you get

consistent results.- You set up a control experiment for comparison (usually what would occur under normal conditions)Example: 3 plants = 16 hours of ultraviolet light, 3 plants =

8 hours of ultraviolet light. Control might be 3 plants = _______ hours of ultraviolet light.

Step 5: Analyze Data and Make Conclusions.

- Write down any observations you see during the experiments (how do the leaves look? Is the plant blooming? How many blooms?)

- Take measurements on a regular basis (I.e., twice a week.) After about 5 weeks, take your final measurements.

- Compare each experiment from beginning to end. Remember, you are relying on actual measurements, not the way the plant “looks”!

How many times do you perform an experiment to ensure accuracy? A real experiment is performed many, many times by a hierarchy of scientists. However, for a classroom project, all controlled and uncontrolled experiments are performed a minimum of 3 times each, as long as the results (from each experiment) are very similar.

Example: Plant growth with sunlight: 3.5cm; 3.3 cm; and 3.7 cm

They mean slightly different things!

Accuracy is how close a measured value is to the actual (true) value.

Precision is how close the measured values are to each other.

So, if you are playing soccer and you always hit the left goal post instead of scoring, then you are not accurate, but you are precise!

Based on your experiment results and observations, did you prove or disprove your hypothesis?

Did you observe anything that may modify your final conclusion? (for example, what if your full sun plant had a lot of brown spots on its leaves? Is full sun best?)

Step 6: Make predictions. - Look carefully at your observations and

data.- How can this information be useful in the

future?- What are some changes (related to your

findings) that can be made to future experiments?

A true scientist does not allow a bias to occur while following the steps.

A bias is when the scientist chooses certain trials over others, often if the results appear “favorable.”

Bias can be eliminated through frequent trials, keeping accurate notes and measurements, and ensuring the results are repeatable by others. To do otherwise can lead to loss of respect, accreditation, and (in extreme cases), criminal charges.