BellringerBellringer

Define these words: (use Ch 1 of Define these words: (use Ch 1 of your book)your book)

ScienceScience Scientific methodsScientific methods HypothesisHypothesis Controlled experimentControlled experiment VariableVariable

A Controlled A Controlled ExperimentExperiment

Part of the scientific methodPart of the scientific method

Review-Scientific MethodReview-Scientific Method

Problem/ QuestionProblem/ Question Observations/Research Observations/Research Hypothesis Hypothesis ExperimentExperiment Data/ResultsData/Results ConclusionConclusion Communicate ResultsCommunicate Results

VariablesVariables A controlled experiment tests only one variable A controlled experiment tests only one variable

and all other factors remain the same.and all other factors remain the same. Variable: A factor that can change. A variable Variable: A factor that can change. A variable

can change other factors when it changes.can change other factors when it changes.Examples of variables:Examples of variables:

-Temperature-Temperature-Light-Light- Open vs. Closed container- Open vs. Closed container-Location-Location-Time-Time-Elevation-Elevation-Pressure-Pressure

The independent variable is the variable that is purposely changed. It is the manipulated variable.

The dependent variable changes in response to the independent variable. It is the responding variable.

VariablesVariables are things that change.

Independent vs. Dependent Independent vs. Dependent Variables Variables

The The dependent variabledependent variable is a factor that is a factor that changes because the changes because the independent variable independent variable changes. However the independent variable changes. However the independent variable is not changed by the dependent variable.is not changed by the dependent variable.

Example:Example: Elevation and Boiling temperature Elevation and Boiling temperature of water. The boiling temperature of water of water. The boiling temperature of water changes because of changes in elevation. changes because of changes in elevation. Changes in the boiling temperature of water Changes in the boiling temperature of water do not change elevation. do not change elevation.

Constants or Controlled Variables in an Experiment

What are constants in an experiment?

Factors that are kept the same and not allowed to change.

It is important to control all but one variable at a time to be able to

interpret data

ControlControl

-A variable or factor that does not -A variable or factor that does not change in the experiment. It remains change in the experiment. It remains constant. constant.

In a Controlled experiment only one In a Controlled experiment only one variable is allowed to change at a variable is allowed to change at a time. Everything else remains time. Everything else remains constant.constant.

Experimental ErrorExperimental Error

Bias (what you expect to happen prevents Bias (what you expect to happen prevents you from observing what you from observing what actually actually happens)happens)

Testing more than one independent Testing more than one independent variable.variable.

Not having a control group.Not having a control group. Not having constants.Not having constants. Not using a large enough test group.Not using a large enough test group. Not repeating the experiment enough Not repeating the experiment enough

times.times.

OBSERVATIONS: Flies land on meat that is left uncovered. Maggots appear on the meat.HYPOTHESIS: Flies produce maggots.

VARIABLES

Controlled Variables:jars, type of meat,location, temperature,time

Independent Variables:gauze (keeps flies away from meat)

Uncovered jars Covered jars

After several days

Maggots appear No maggots appear

Dependent Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Francisco Redi & Francisco Redi & Spontaneous GenerationSpontaneous Generation

ReplicatesReplicates In an experiment multiple copies of In an experiment multiple copies of

the experiment are done at the same the experiment are done at the same time.time.

This is to ensure that the results are This is to ensure that the results are accurate (true) and not due to a accurate (true) and not due to a mistake, error or chance event.mistake, error or chance event.

TreatmentsTreatments

Set of variables in the experiment Set of variables in the experiment that are the same in each group of that are the same in each group of replicates.replicates.

2 Treatments 2 Treatments CoveredCovered

UncoveredUncovered

ProblemProblemWhich pinto beans will grow better, those in

fresh water or salt water?

ReviewReview

What is a controlled experiment?• An experiment with one group of test subjects being exposed to the variable, and one that is not treated with the _________ being tested!

variable

What is the variable being tested in the pinto bean experiment?Salt (How it EFFECTS the pinto bean growth)

Controlled Experiment

Experimental Group

Control Group

In the pinto bean experiment, which is the control group and which is the

experimental group?

What are the groups in a controlled experiment?

-Gets NORMALTreatment

(No Variable).-Used for comparison

Gets the VARIABLEyou are testing.

Control Group: Experimental Group: Fresh water beans Salt Water Beans

1.1. Independent (manipulated)Independent (manipulated)–is what the –is what the scientist controls or changes or it affects scientist controls or changes or it affects something. (SALT Affects Bean Growth)something. (SALT Affects Bean Growth)

2.2. Dependent (responding)Dependent (responding)–is the variable that –is the variable that is observed and that is affected by the is observed and that is affected by the independent variable. (BEAN GROWTH)independent variable. (BEAN GROWTH)

Controlled Experiment Variables

Variables: factors that can change

What are the two types of variables?

Constants: are exactly the same for both the Constants: are exactly the same for both the control and experimental groups. Both groups control and experimental groups. Both groups

should be treated exactly the same except for the should be treated exactly the same except for the variable variable being tested.being tested.

What are the constants in the pinto bean experiment?

Experiment (Controlled) Constants

• Beaker Size

• Amount of Water

• Brand of Pinto Beans

Exit AssignmentExit Assignment

Identify the variables in this Identify the variables in this experiment:experiment:

Can tomato plants grow without Can tomato plants grow without being exposed to sunlight?being exposed to sunlight?

What is the independent variable? What is the independent variable? Dependent variable? Constants?Dependent variable? Constants?

How would you set up the How would you set up the experiment to test this question?experiment to test this question?