The Scientific The Scientific MethodMethod
Making a Good ExperimentMaking a Good Experiment
The Scientific MethodThe Scientific Method
Is the driving force for all scientific Is the driving force for all scientific progression.progression.
Is based on gathering evidence through Is based on gathering evidence through an experiment and drawing a conclusion an experiment and drawing a conclusion from that evidence.from that evidence.
RememberRemember
The scientific method does not strive to The scientific method does not strive to prove what is true.prove what is true.
It is used to disprove what is It is used to disprove what is false/impossiblefalse/impossible
This is why we deal with Theories in This is why we deal with Theories in science, because we can never know with science, because we can never know with 100% certainty, if our findings are correct.100% certainty, if our findings are correct.
RememberRemember
No matter how much evidence you No matter how much evidence you have, or certain of the truth you have, or certain of the truth you might be, you can never be 100% might be, you can never be 100% certain.certain.
Misinformed in the past:Misinformed in the past: Four element theory.Four element theory. Earth being flat.Earth being flat. Pleasant scents fighting sickness.Pleasant scents fighting sickness.
Where it BeginsWhere it Begins
It all starts with a Question. What It all starts with a Question. What do you really want to find out?do you really want to find out?
I want to find out what kind of liquid I want to find out what kind of liquid carrots will grow best in.carrots will grow best in.
I want to know whether a 2L bottle I want to know whether a 2L bottle of pop will go flat faster if I do not of pop will go flat faster if I do not squeeze the bottle before sealing it.squeeze the bottle before sealing it.
Background ResearchBackground Research
It is important to look into what has It is important to look into what has already been discovered in this area already been discovered in this area before you start an experiment.before you start an experiment.
Research the topic of your Research the topic of your experiment and educate yourself experiment and educate yourself before you begin.before you begin.
The HypothesisThe Hypothesis
A prediction about the results of the A prediction about the results of the experiment before you run it.experiment before you run it.
Stated in an “if ______ then ______” formatStated in an “if ______ then ______” format
IF carrots are given a food source with IF carrots are given a food source with more nutrients, such as apple juice or more nutrients, such as apple juice or orange juice, THEN they will grow orange juice, THEN they will grow faster/stronger.faster/stronger.
Note: it is okay for a hypothesis to be Note: it is okay for a hypothesis to be wrong**wrong**
The ExperimentThe Experiment
HypothesisHypothesis MaterialsMaterials – all materials used in the – all materials used in the
experimentexperiment Procedure Procedure – a step by step set of – a step by step set of
instructions, written in past tense. instructions, written in past tense. Exact numbers/amounts should be used.Exact numbers/amounts should be used.
ObservationsObservations – what you observed – what you observed ConclusionsConclusions – based on obs. Was your – based on obs. Was your
hypothesis right or wrong?hypothesis right or wrong?
Carrots Exp.Carrots Exp.
Hypothesis: Carrots fed a solution of Hypothesis: Carrots fed a solution of high nutrients, such as apple juice or high nutrients, such as apple juice or orange juice, will grow faster/better orange juice, will grow faster/better than other carrotsthan other carrots
Materials: carrot tops, soil, 4x4 Materials: carrot tops, soil, 4x4 containers, apple juice, orange juice, containers, apple juice, orange juice, water, pepto bismol, colawater, pepto bismol, cola
Carrots Exp.Carrots Exp. Procedure:Procedure:
top ends of carrots were cut off and planted top ends of carrots were cut off and planted in two inches of soil in the 4x4 container.in two inches of soil in the 4x4 container.
Carrots were placed in a well lit area, each Carrots were placed in a well lit area, each susceptible to the same conditionssusceptible to the same conditions
Fluid solutions were made at a Fluid solutions were made at a concentration of half water and half testable concentration of half water and half testable substance.substance.
Each carrot was “fed” once daily with each Each carrot was “fed” once daily with each of the respective solutions: water, OJ, AJ, of the respective solutions: water, OJ, AJ, Pepto and cola.Pepto and cola.
Observations were taken over a period of 2 Observations were taken over a period of 2 weeks on growth and appearance of carrots.weeks on growth and appearance of carrots.
Carrots Exp.Carrots Exp.
Observations: over a 2 week periodObservations: over a 2 week period Water – grew to a height of 10 inchesWater – grew to a height of 10 inches Apple juice – grew to a height of 2 inches, Apple juice – grew to a height of 2 inches,
but shrivelled and died after 6 daysbut shrivelled and died after 6 days Orange juice – did not grow. Carrot top Orange juice – did not grow. Carrot top
actually shrivelled and blackened over the 2 actually shrivelled and blackened over the 2 weeks.weeks.
Pepto Bismol – growth was stunted and Pepto Bismol – growth was stunted and insignificant.insignificant.
Cola – carrot blacked and died within 3 days.Cola – carrot blacked and died within 3 days.
Carrots Exp.Carrots Exp. Conclusion: It would seem that the “high Conclusion: It would seem that the “high
nutrient solutions” were also high in acid nutrient solutions” were also high in acid content, which seemed to outright kill the content, which seemed to outright kill the plants.plants.
Orange juice and had prompt, devastating Orange juice and had prompt, devastating effects.effects.
Cola immediately destroyed the plant, due to Cola immediately destroyed the plant, due to its’ high acid and sugar content and lack of its’ high acid and sugar content and lack of nutrients.nutrients.
Apple juice, slightly less harsh, allowed the Apple juice, slightly less harsh, allowed the plant to grow at first, until the concentration in plant to grow at first, until the concentration in the soil was too high.the soil was too high.
Carrots Exp.Carrots Exp.
Water worked best, as expected.Water worked best, as expected.
The pepto bismol results were The pepto bismol results were curious and will need to be curious and will need to be investigated further. There are investigated further. There are many artificial compounds in the many artificial compounds in the substance which could have effected substance which could have effected the plant in a myriad of ways.the plant in a myriad of ways.
Designing a good Designing a good ExperimentExperiment
Making a good experiment can be hard.Making a good experiment can be hard. 1. Test only one variable at a time!!!!!! 1. Test only one variable at a time!!!!!!
(Manipulated variable)(Manipulated variable) You need to control all of the variables other You need to control all of the variables other
than the one you are testing. (controlled than the one you are testing. (controlled variables)variables)
If you are testing how different amounts of If you are testing how different amounts of water will affect plant growth than you need water will affect plant growth than you need to control container size, type/amount of soil, to control container size, type/amount of soil, amount of light, source of light, temp of room amount of light, source of light, temp of room etc.etc.
Designing a good Designing a good ExperimentExperiment
2. You need to have a “control”2. You need to have a “control”
Control: a specimen/part of the Control: a specimen/part of the experiment where the manipulated experiment where the manipulated variable is unchanged.variable is unchanged.
A control gives you something to A control gives you something to compare the other results to.compare the other results to.
Designing a good Designing a good ExperimentExperiment
3.3. Do as many trials and samples as Do as many trials and samples as possible.possible.
Having more samples in your Having more samples in your experiment reduces the chances of a experiment reduces the chances of a mistake or error occurring.mistake or error occurring.
Single trial experiments don’t tell you Single trial experiments don’t tell you much. How do you know that one of much. How do you know that one of your plants wasn’t just sick or defective?your plants wasn’t just sick or defective?
Designing a good Designing a good ExperimentExperiment
1. Test only one variable at a 1. Test only one variable at a time!!!!!! (Manipulated variable)time!!!!!! (Manipulated variable)
2. You need to have a “control”2. You need to have a “control” 3.3. Do as many trials and samples as Do as many trials and samples as
possible.possible.
What’s wrong with these What’s wrong with these experimentsexperiments
Joey Bloggs wanted to test how long it Joey Bloggs wanted to test how long it would take ice to freeze if it had would take ice to freeze if it had different amounts of salt dissolved in it.different amounts of salt dissolved in it.
He set up 5 groups of 4 cups with He set up 5 groups of 4 cups with varying amounts of salt and split them varying amounts of salt and split them up between two different freezers.up between two different freezers.
He checked his samples every 5 He checked his samples every 5 minutes to see how frozen they were.minutes to see how frozen they were.
What about his samples is not What about his samples is not consistent?consistent?
What’s wrong with these What’s wrong with these experimentsexperiments
Kevin wanted to test the strength of Kevin wanted to test the strength of different bridge designs: a dome, a different bridge designs: a dome, a square, a triangular and a diamond square, a triangular and a diamond shaped bridge.shaped bridge.
Each bridge was made out of a different Each bridge was made out of a different material. Wood, lego, K’NeX and straws.material. Wood, lego, K’NeX and straws.
Why will results be difficult to draw from Why will results be difficult to draw from this test?this test?
What’s wrong with these What’s wrong with these experimentsexperiments
Stitch was trying to determine which Stitch was trying to determine which fertilizer would make his plants grow fertilizer would make his plants grow best.best.
He set up 4 sets of 3 bean plants, each He set up 4 sets of 3 bean plants, each to receive a different fertilizer.to receive a different fertilizer.
Set1 – NewGro, Set 2 – DoubleGroSet1 – NewGro, Set 2 – DoubleGro
Set 3 – UltraGrow Set 4 – KindaGROSet 3 – UltraGrow Set 4 – KindaGRO
What was he missing?What was he missing?
What’s wrong with these What’s wrong with these experimentsexperiments
The Mythbusters tested how radiation The Mythbusters tested how radiation would affect different insect.would affect different insect.
They took a equal numbers of three species They took a equal numbers of three species of insect and subjected them to deadly of insect and subjected them to deadly gamma rays.gamma rays.
After one trial, they drew decisive After one trial, they drew decisive conclusions and published them on their conclusions and published them on their television show.television show.
What was their error?What was their error?
