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Ch 1 Science Skills

Science involves asking questions about nature and then finding ways to answer them.

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Branches of ScienceNatural science is generally divided into three branches: physical science, Earth and space science, and life science.

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Physical science focuses on nonliving things.Chemistry is the study

of the composition, structure, properties, and reactions of matter.

Physics is the study of matter and energy and the interactions between the two through forces and motion.

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Scientific Method

There is no one absolute “Scientific Method”-it is simply a list of general steps scientists take to solve problems or answer questions

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1) Come up with a question…

The heart of science is looking around you and wondering-how…?-why…?-what if…?

The question should be answerable by performing an experiment.

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2) Create a hypothesis-one possible answer to your question…

A hypothesis is an educated statement or guess about how something works that can be proven right or wrong by performing an experiment.

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3) Design an experiment…

Think of how you can test your hypothesis. Usually, you only want to test one thing or one variable at a time.

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4) Perform experiment and collect data…

Perform the experiment you designed . Observe and record what happens in as much detail as possible!

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5) Draw conclusions…

Sometimes it is not clear what the results of the experiment were.

Often repeating the experiment or designing another one is necessary.

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6) Communicate your results…

*Scientists around the world cooperate and share their work so that others can benefit from what they’ve learned.

*Other scientists look at the work to see if they agree in a process called peer review.

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Testing a Hypothesis In an experiment, any factor that can change is called a variable.

• The manipulated/independent variable causes a change.

• The responding/dependent variable changes in response to the manipulated variable.

• A controlled experiment is an experiment in which only one variable, the manipulated variable, is deliberately changed at a time.

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Theories vs. Laws of scienceA scientific theory is a well-tested explanation for a set of observations or experimental results. Once a hypothesis has been supported in repeated experiments, scientists can begin to develop a theory.

After repeated observations or experiments, scientists may arrive at a scientific law.

A scientific law is a statement that summarizes a pattern found in nature. A scientific law describes an observed pattern in nature without attempting to explain it. The explanation of such a pattern is provided by a scientific theory.

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Scientific Notation

Scientific notation is a way of expressing a value as the product of a number between 1 and 10 and a power of 10.

For example, the speed of light is about 300,000,000 meters per second. In scientific notation, that speed is 3.0 × 108 m/s. The exponent, 8, tells you that the decimal point is really 8 places to the right of the 3.

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For numbers less than 1 that are written in scientific notation, the exponent is negative.

For example, an average snail’s pace is 0.00086 meters per second. In scientific notation, that speed is 8.6 × 10-4 m/s.

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SI units of measurement

Base Units and Derived Units SI is built upon seven metric units, known as base units.

• In SI, the base unit for length, or the straight-line distance between two points, is the meter (m).

• The base unit for mass, or the quantity of matter in an object or sample, is the kilogram (kg).

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Seven metric base units make up the foundation of SI.

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Additional SI units, called derived units, are made from combinations of base units.

• Volume is the amount of space taken up by an object.

• Density is the ratio of an object’s mass to its volume:

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Metric Prefixes The metric unit is not always a convenient one to use. A metric prefix indicates how many times a unit should be multiplied or divided by 10.

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Limits of measurements Precision is a gauge of how exact a measurement I Another important quality in a measurement is its

accuracy. Accuracy is the closeness of a measurement to the actual value of what is being measured. s.

For example, a more precise time can be read from the digital clock than can be read from the analog clock. The digital clock is precise to the nearest second, while the analog clock is precise to the nearest minute.

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Significant figures are all the digits that are known in a measurement, plus the last digit that is estimated.

Whenever you work a problem in science you need to keep significant figures in mind. Your answer should have the same number of significant figures as your knowns (the information you were given)

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Measuring Temperature

The two temperature scales that you are probably most familiar with are the Fahrenheit scale and the Celsius scale.

• A degree Celsius is almost twice as large as a degree Fahrenheit.

• You can convert from one scale to the other by using one of the following formulas.

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The SI base unit for temperature is the kelvin (K).

To convert between K And C use the following formula;

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Presenting Data In order for news to be

useful, it must be reported in a clear, organized manner. Like the news, scientific data become meaningful only when they are organized and communicated. Communication includes visual presentations, such as these graphs.

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Line Graphs

A line graph is useful for showing changes that occur in related variables.

• In a line graph, the manipulated variable is generally plotted on the horizontal axis, or x-axis.

• The responding variable is plotted on the vertical axis, or y-axis, of the graph.

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Bar Graphs

A bar graph is often used to compare a set of measurements, amounts, or changes.

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Circle or Pie graph

If you think of a pie cut into pieces, you have a mental model of a circle graph. A circle graph shows how a part or share of something relates to the whole.