science is a way of thinking, questioning, & gathering evidence. so, how do scientists gather...

Science is a way of thinking, questioning, & gathering evidence.

So, how do scientists gather evidence & make discoveries?

The Scientific Method

Scientists study life using the scientific method.

• Follow steps of a scientific investigation (inquiry)

a. Observe: make an observation of the world around you

Scientists look critically & attempt to avoid all sources of bias in an

observation.

2 Types of Observations

• Qualitative: an observation of a characteristic or quality– The plant is dark green.

• Quantitative: a numerical observation– The graduated cylinder

contains 6.6 mL of water.

The sky is blue.

A. QualitativeB. Quantitative

Qualitative!

There are 4 clouds.


Quantitative!

There are 3 hills.


Quantitative!

The 1st hill is small.


Qualitative!

The clouds are small.


Qualitative!

There are 38 birds.


Quantitative!


b. Ask a question: based on your observation, ask a question to investigate

You want your question to be answerable!

“Which color is the prettiest?” is not a testable question.


c. Research: look in books, journals, internet, etc. to make additional observations & research about your question


d. Formulate a hypothesis: propose an answer or explanation to your question. At the end of the investigation, you will either accept or reject your hypothesis.

The hypothesis must be testable!


e. Perform a controlled experiment: develop & use the experimental design to test your hypothesis

This is the actual hands-on part of the project.

Here, you carry out your manipulation & compare the

results with results from a control setting.

Variables in an Experiment(factors being tested)

• Independent Variable: variable being manipulated (changed on purpose)– On a graph, found on the x-axis

• Dependent Variable: variable that responds– On a graph, found on the y-axis

• Control Group: the group where the independent variable is not applied; used for comparisons

• Controlled Variables: variables that are held constant

In an experiment, ONLY CHANGE 1 VARIABLE AT A TIME!

Does Miracle Grow help plants grow larger?

How would you set up this experiment?

• For this experiment, you need 2 plants (a test group & a control group).

• 1 plant will be planted in regular soil, but the other will be planted in Miracle Grow soil.

Which plant is my control group?

The plant with regular soil is the control group.

The plant with the Miracle Grow is the test group.


• There should only be 1 difference between the test group & the control group!– In this experiment, the only difference is the type of soil

used (regular or Miracle Grow).

• ALL OTHER FACTORS MUST REMAIN THE SAME!– Controlled variables: same type of plant, same amount of

sunlight, same amount of water, etc.


• The 1 difference between the test group & the control group is the independent variable.

So what is the independent variable in this experiment?

The independent variable is the type of soil used!

This is what you changed on purpose.


• The variable that changes in response to the independent variable is the dependent variable.

What is the dependent variable in this experiment?

The dependent variable is the plant growth!

This is what you are measuring.

The Dependent Variable

DEPENDSON

The Independent Variable

(Plant growth depends on the type of soil.)


• Independent Variable: type of soil used

• Dependent Variable: amount of plant growth

• Controlled Variables: amount of sunlight, water, etc.

• Control Group: plant with regular soil

• Test Group: plant with Miracle GrowNotice that

these are not the same thing!

Students at DHS wanted to test if paper weight affects the distance paper airplanes fly. The same type of paper airplanes were folded from three different weight papers. The planes were thrown in the mall area to measure the distance they

would fly. What are the following variables?

1. Independent Variable? ___________________

2. Dependent Variable? ____________________

Weight of paper

Distance the plane flew

A group of students was asked to compare the taste of lemonade. One glass was from a pitcher made with one cup of sugar. The second glass was made from a pitcher with two cups of sugar. Both pitchers used the same amount of water,

lemon juice, and ice. What are the following variables?

1. Independent Variable? ___________________

2. Dependent Variable? ____________________

Amount of Sugar

Taste

Squidward loves playing his clarinet and believes it attracts more jellyfish than any other instrument he has played. In order to test his hypothesis, Squidward played a song on 3 instruments for a total of 5

minutes and counted the number of jellyfish he saw in his front yard. He also recorded the number of jellyfish he observed when he was not

playing an instrument.

1. What is the control group? _____________________________

2. What is the independent variable? _______________________

3. What is the dependent variable? ________________________

Instrument

3 trials with no music

Number of jellyfish

How do scientists study life?

f. Collect Data: perform analysis on the data using graphs & charts

How do scientists study life?

g. Draw conclusions: state whether or not the evidence supports the hypothesis based on your data & analysis

h. Report back to the community!

science is a way of thinking, questioning, & gathering evidence. so, how do scientists gather...

Documents

test group

qualitative b

miracle grow

scientific method

yaxis control group

independent variable

controlled experiment

control setting