Scientific Methods

Vocabulary WordsRecord these in your journal. Titles the page

“Vocbulary Words”.

• Hypothesis– An educated prediction that can be tested. It describes in

concrete terms what you expect to happen.

• Theory– An explanation that has been tested many times, resulting in the

same conclusion.

• Variable– A factor or condition in an experiment that changes or can be

changed.

• Independent Variable (Manipulated)– A factor or condition in an experiment that is changed on

purpose.– This is the X-axis (bottom) of a graph.

Vocabulary Words

• Dependent Variable– A factor or result in an experiment that changes as a result of

the independent variable.– It is the data of an experiment.– This is the Y-axis (side) of a graph.

• Constant– A factor or condition that is kept the same in all trials of an

experiment.

• Control– A set up without the variable being tested.

What Science Is and Is Not

• What does it mean to say that an approach to a problem is scientific?

• The goal of science is:

– to investigate and understand the natural world

– to explain events in the natural world

– to use those explanations to make useful predictions.

What Science Is and Is Not

• Features of science include:

– deals with the natural world.

– collecting and organizing data in careful, orderly way.

– looks for patterns and connections.

– propose explanations that can be tested.

• Science also refers to the body of knowledge that scientists have built up after years of using this process.

Data

• There are two main categories of data.

– quantitative data are expressed as numbers, obtained by counting or measuring.

– qualitative data are descriptive and involve characteristics that can't usually be counted.

• The researcher might make the qualitative observations that “the scar appears old” and “the animal seems healthy and alert.”

• Scientists will use data to make inferences.

Inferences

• An inference is a logical interpretation based on prior knowledge or experience.

• For example, a researcher might be testing water in a reservoir.

• Because they cannot test all the water, they collect water samples from several different parts of the reservoir.

• If all the samples are clean enough to drink, they may infer that all the water is safe to drink.

Types of Investigations

• Descriptive Investigation

– Involves describing or quantifying parts of the world

– Has a research question, procedures, and conclusion.

– Used when little is known about the topic.

– No hypothesis or prediction.

– Uses observe, describe, list, identify as key words.

Types of Investigations

• Comparative Investigation

– Involves collecting data on different populations/organisms under different conditions to make a comparison.

– Has a research question, possible hypothesis, procedures, and conclusion.

– Can have independent and dependent variables.

– Uses compare/contrast, similarity/difference categorize as key words.

Types of Investigations

• Experimental Investigation

– Involves designing a test in which variables are changed, controlled, and measured in an effort to gather evidence to support a hypothesis.

– All known variables have been identified.

– Has a research question, hypothesis, procedures, control, and conclusion.

– Has independent and dependent variables.

– All factors are held constant except the independent variable.

Warm-Up

• There are three types of investigations.

• Read each of the following questions and determine which type of investigation it is.

• Write your answer on a sheet of paper. Be sure your first and last name and period number is on the paper.

1. QUESTION: How does the amount of potato affect its reaction with a fixed amount of hydrogen peroxide?

2. QUESTION: Which vegetable shows the greatest reaction to hydrogen peroxide?

3. QUESTION: What happens when a piece of potato is added to hydrogen peroxide?

Warm-Up

4. Which type of investigation includes these key words: observe, describe, list, identify?

5. Which type of investigation involves collecting data on different populations/organisms under different conditions to make a comparison?

6. Which type of investigation has all factors held constant except the independent variable?

How Scientists Work

Scientific Methods

Scientists work hard to discover new facts and to solve problems.

The way they do this is often referred to as the “scientific method”.

No matter what method scientists use to solve their problem, there are always steps that must be followed.

State the Problem

Stating the problem, or coming up with a question, allows the scientist to identify

what they need to do.

Gather Information

This helps the scientist find out how much information they know, and need to know, about

the problem.

Suggesting a Hypothesis

It is not an educated guess.A hypothesis is a suggested solution based on prior

knowledge

Performing an Experiment

This is done to test the hypothesis.Most experiments contain two parts; the variables and a

control.The variable is the part of the experiment that is being

tested.The control is the part of the experiment that does not

change.

Recording and Analyzing Data

Information that is gathered from the experiment is data.

Data is often displayed as a graph, or graphs.

Stating a Conclusion

Based on the analysis of the data.The conclusion either agrees with the hypothesis or it

doesn’t.The conclusion can also lead to other questions which leads

to more experimentation.

1. Work with the members of your table.2. Using the scientific method, write a procedure to test

your observation of the following.

– You have three gardens in your yard.– One on the east side, one on the west side, and one on the

south side.– The plants are all the same type, but you notice that the plants

on the south side are at least 2 inches taller than the other plants on the east or west sides.