1

Introduction to Science Investigations

Chapter 1, page 4-26.

2

Branches of Science

Biological Sciences– Botany– Zoology– Ecology

Physical Sciences– Physics– Chemistry

Earth Sciences– Geology– Meteorology

3

Theory vs. Law

A scientific law describes a process in nature that can be tested by repeated experiments.

A scientific theory is an explanation of how a natural process works.

4

Scientific Method

1. State a problem.2. Research.3. Form a hypothesis.4. Test the hypothesis.5. Collect data.6. Analyze data.7. Form a conclusion.8. Report your results.

5

Observations Quantitative observations are

made by making measurements. Qualitative observations are

made by observing using our senses.

Inference is the act or process of deriving a conclusion based solely on what one already knows.

Fact is defined as something that is true, something that actually exists, or something that can be verified according to an established standard of evaluation.

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The Experiment

An experiment must test one variable at a time.

During the experiment, measurements must be made.

All observations must be recorded in such a manner that the experiment can be repeated with similar results.

7

Variables

The independent variable is the one condition that the experimenter is changing (measuring).

– Only one independent variable at a time in an experiment.

The dependent variable is what changes as a direct result of the independent variable (testing).

8

Graphing Variables

The independent variable is placed on the x-axis of the graph.

The dependent variable is placed on the y-axis of the graph.

9

Control

The control is an experimental group that does not receive the condition of the independent variable.

– Standard for comparison. The constants are those

conditions which are the same for every experimental group.

10

Statistical Analysis Mean is the average and is

computed as the sum of all the observed outcomes  from the sample divided by the total number of events.

Mode of a set of data is the number with the highest frequency. 

Median is the middle score. The variance and standard

deviation describe how spread out the data is.

11

SI Measurements

Length is measured in meters.

Mass is measured in grams.

Volume is measured in liters.

Weight is measured in Newtons.

Temperature is measured in Kelvin.

12

Prefixes for Metric Units (Powers of Ten)

Prefix Symbol Meaning Multiple of base unit

kilo- k thousand 1000mega- M million 1000000giga- G billion 1000000000deci- d tenth 0.1centi- c hundredth 0.01milli- m thousandth 0.001micro- μ millionth 0.000001nano- n billionth 0.000000001

13

Significant Figures

Significant figures-a prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement.

Sig figs determine the precision of the measurement depending on the instrument used to make the measurement.

Rule 1: Non-zero digits are always significant.

Rule 2: Any zeros between two significant digits are significant.

Rule 3: A final zero or trailing zeros in the decimal portion ONLY are significant.

14

Accuracy vs. Precision

Accuracy is a description of how close a measurement is to the true value of the quantity measured.

Precision is the exactness of a measurement.

accurate

precise

accurate and precise

15

Scientific Notation

Scientific notation is a method of expressing a quantity as a number multiplied by 10 to the appropriate power.

This is used to express very large numbers or very small numbers.

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