55thth Grade Investigation and Grade Investigation and Experimentation SkillsExperimentation Skills

Variables Variables VariablesVariables

Something in the experiment that will change. Something in the experiment that will change. Vari means to change. Vari means to change.

In an experiment, the scientist deals with 3 In an experiment, the scientist deals with 3 types of variables.types of variables.

1) Independent variable1) Independent variable2) Dependent variable2) Dependent variable3) Controlled variables3) Controlled variables

To make an investigation scientific you must To make an investigation scientific you must have an independent variable, a dependent have an independent variable, a dependent variable, and controlled variablesvariable, and controlled variables

Independent VariablesIndependent Variables

Independent VariablesIndependent VariablesThe variable that is The variable that is purposefully purposefully changedchanged (scientist will change it) (scientist will change it)

Can have only Can have only ONEONE in an investigationin an investigation

Examples: Examples: amount of water, time, amount of water, time, mass, temperature, amount of sunlightmass, temperature, amount of sunlight

Dependent VariableDependent Variable

Dependent VariableDependent VariableThe variable that The variable that changes in responsechanges in response to to the independent variable (usually the independent variable (usually measuredmeasured or or recordedrecorded in an in an investigation) investigation)

Examples: Examples: time it takes to evaporate, time it takes to evaporate, bounce height of the ball, distance bounce height of the ball, distance traveled, change in plant heighttraveled, change in plant height

Controlled variablesControlled variables

Controlled variablesControlled variablesThings that are Things that are kept the kept the samesame throughout the throughout the entireentire investigation investigation

Examples: Examples: same location, same same location, same temperature, same conditionstemperature, same conditions

Maria grew four plants in an experiment about plant growth. The table below shows the design and results of Maria’s experiment.

You can see that Maria has 4 plants. She is watering all plants the same, and all the plants are receiving the same amount of plant food every day. These are called the CONTROLLED variables.

Each plant receives a different amount of sunlight each day. This is the INDEPENDENT variable because it is the variable that is being changed.

Maria is measuring the height of the plant at the end of the experiment. This is the DEPENDENT variable because it is the variable being measured.

Review Question # 1Review Question # 1Carlos put identical daisies on the windowsill Carlos put identical daisies on the windowsill

next to each other. They both received next to each other. They both received 200 mL. of water daily. One plant 200 mL. of water daily. One plant received 10 mL. of fertilizer every day and received 10 mL. of fertilizer every day and the other did not. the other did not.

What is the independent variable in Carlos’ experiment?

A the growth of the flower

B the amount of water

C the addition of fertilizer

D the amount of sunlight

Answer Question # 1Answer Question # 1

CC The The independent variableindependent variable is the is the variable that is variable that is being changedbeing changed in the in the experiment. In Carlos’ experiment, only experiment. In Carlos’ experiment, only one plant is receiving the fertilizer, so the one plant is receiving the fertilizer, so the addition of fertilizer is the independent addition of fertilizer is the independent variable. The growth of the flower is variable. The growth of the flower is being being measuredmeasured and is the and is the dependent variabledependent variable. . The amount of water, amount of sunlight, The amount of water, amount of sunlight, and type of plant are and type of plant are all the sameall the same and are and are all all controlled variablescontrolled variables. .

Steps of the Scientific InvestigationSteps of the Scientific Investigation

Five Steps to the Scientific InvestigationFive Steps to the Scientific Investigation– Scientists follow the steps of the scientific Scientists follow the steps of the scientific

investigation during an experimentinvestigation during an experiment

Five Steps: Five Steps: 1.1. Problem QuestionProblem Question

2.2. Hypothesis Hypothesis

3.3. Procedure/Experiment Procedure/Experiment

4.4. Results/Analysis of the Data Results/Analysis of the Data

5.5. Conclusion Conclusion

Problem QuestionProblem Question

Problem QuestionProblem Question – what we are trying to – what we are trying to find out/ research find out/ research

Must include the Must include the independent variableindependent variable and and dependent variabledependent variable

Example: Example: How does the amount of How does the amount of sunlight affect the growth of the plantsunlight affect the growth of the plant??

In this example, amount of sunlight is the In this example, amount of sunlight is the independent variableindependent variable and growth of the and growth of the plant is the plant is the dependent variabledependent variable..

Review Question # 2Review Question # 2Which of the following questions is testable in Which of the following questions is testable in

a scientific investigation?a scientific investigation?AA Are dogs better pets than cats?Are dogs better pets than cats?

BB Are dogs happy when they are Are dogs happy when they are walked?walked?

CC Are cats more active at night than Are cats more active at night than during the day?during the day?

DD Are cats easier to take care of than Are cats easier to take care of than dogs?dogs?

Answer Question # 2Answer Question # 2

CC A testable question is one that you A testable question is one that you can can actually collect dataactually collect data for. Choices A, for. Choices A, B and D are all opinions. How would you B and D are all opinions. How would you test that the animal is better, happier, or test that the animal is better, happier, or easier to take care of? However, you easier to take care of? However, you could test to see if cats are more active could test to see if cats are more active than dogs at night by observing both than dogs at night by observing both animals during the night and collecting animals during the night and collecting data for what you observe. data for what you observe.

HypothesisHypothesisForm a HypothesisForm a HypothesisHypothesis: an Hypothesis: an educated guesseducated guess that is tested that is tested

over and over again.over and over again.Gives a Gives a solutionsolution to the problem question to the problem question

Tells Tells whywhy your solution will work your solution will work

ExampleExample: If: If the the amount of sunlightamount of sunlight increases,increases, thenthen the the height of the plantheight of the plant will will increaseincrease because because I know that my plant at I know that my plant at home always grows more when it is in the home always grows more when it is in the sun a lot. sun a lot.

Procedure/ExperimentProcedure/ExperimentContains Contains all information to all information to perform the experimentperform the experiment: : independent variable, independent variable, dependent variable, dependent variable, controlled variables, controlled variables, materials, and suppliesmaterials, and supplies

The procedure might include The procedure might include diagrams, drawings of the diagrams, drawings of the experiment set-up, and steps experiment set-up, and steps listed with numbers.listed with numbers.

Results/Analysis of the DataResults/Analysis of the DataResults are presented in charts, data Results are presented in charts, data tables and graphs tables and graphs

Results include data that is your opinion, Results include data that is your opinion, like color change or odor. like color change or odor.

It also includes data that is measured It also includes data that is measured (time, measurement of distance, mass, (time, measurement of distance, mass, temperature, and height)temperature, and height)

Must include all data from the experimentMust include all data from the experiment

ConclusionConclusion• Interpret the data – was Interpret the data – was

your your hypothesishypothesis supported by the data?supported by the data?

• List any sources of error List any sources of error

• List any changes you List any changes you would make the next time would make the next time you conduct the you conduct the experimentexperiment

Review Question # 3Review Question # 3

During the experiment, Carlos wrote on his During the experiment, Carlos wrote on his lab sheet, “I think the plant getting the lab sheet, “I think the plant getting the fertilizer will grow more because my plants fertilizer will grow more because my plants at home always grow more when I put at home always grow more when I put fertilizer in them.”fertilizer in them.”

This statement is an example of:

A a conclusion

B results

C an observation

D a hypothesis

Answer Question # 3Answer Question # 3

DD A A hypothesishypothesis is a is a guessguess that is that is tested. Carlos is stating what he thinks tested. Carlos is stating what he thinks will happen and why. He is not stating a will happen and why. He is not stating a conclusion, what he learned. He is also conclusion, what he learned. He is also not stating results, the data he collected not stating results, the data he collected during the experiment. Carlos is also not during the experiment. Carlos is also not stating an observation, what he saw during stating an observation, what he saw during the experiment. the experiment.

Review Question # 4 4Five Steps in an Investigation:Five Steps in an Investigation:

a) Procedure/Experiment a) Procedure/Experiment b) Hypothesis b) Hypothesis c) Problem Questionc) Problem Questiond) Conclusiond) Conclusione) Results/Analysis of the Datae) Results/Analysis of the Data

George is going to conduct a scientific investigation. In what order should George follow the steps listed above?

A b d e a c

B c b a e d

C a b c d e

D c a d b e

Answer Question # 4Answer Question # 4

BB The five steps of the scientific The five steps of the scientific method in order are: method in order are:

1.1. Problem QuestionProblem Question

2.2. Hypothesis Hypothesis

3.3. Procedure/Experiment Procedure/Experiment

4.4. Results/Analysis of the Data Results/Analysis of the Data

5.5. Conclusion Conclusion

Review Question # 5Review Question # 5

The table shows the time it took to freeze plain water and The table shows the time it took to freeze plain water and water with different amounts of salt. According to the water with different amounts of salt. According to the table:table:

AA   water with more salt takes longer to freeze    water with more salt takes longer to freeze

BB   freezing rates are the same in plain and salt water    freezing rates are the same in plain and salt water

CC   plain water takes longer to freeze   plain water takes longer to freeze

DD   both the water with 5 g salt, and the water with 10 g of salt,    both the water with 5 g salt, and the water with 10 g of salt, froze at the same ratefroze at the same rate

Answer Question # 5Answer Question # 5AA As more salt is added to the water, it As more salt is added to the water, it

takes longer to freeze. This is why salt is takes longer to freeze. This is why salt is put on icy roads. The outside temperature put on icy roads. The outside temperature has to be extremely low for the road to has to be extremely low for the road to freeze because the salt lowers the freeze because the salt lowers the freezing point of the water on the road. freezing point of the water on the road.

The graph shows how many individuals were The graph shows how many individuals were found in a beetle colony. How many more found in a beetle colony. How many more beetles than mealworms were found in this beetles than mealworms were found in this colony?colony?A   5A   5B   8B   8C   14C   14D   32 D   32

Review Question # 6

Answer Question # 6Answer Question # 6BB According to the graph, there are 20 According to the graph, there are 20

beetles and 12 mealworms. Therefore, beetles and 12 mealworms. Therefore, there are 8 more beetles (20-12=8)there are 8 more beetles (20-12=8)

Review Question # 7A scientist was studying a mammal population. The data table shows some of her results.

Which pie chart represents the information in the table?

Answer Question # 7Answer Question # 7CC Out of 205 individuals in the Out of 205 individuals in the

population, about half of them, 104, are population, about half of them, 104, are juveniles. The pie chart should show the juveniles. The pie chart should show the juvenile part of the chart being half, and juvenile part of the chart being half, and males being slightly less than females. males being slightly less than females.

Review Question # 8

Elaine wants to measure the volume of a large pitcher of lemonade. Which units should Elaine use?

A liters

B grams

C meters

D degrees

Answer Question # 8Answer Question # 8

AA The volume of liquids is measured in The volume of liquids is measured in units like liters, milliliters, quarts, and pints.units like liters, milliliters, quarts, and pints.