Chapter One – Part 2Chapter One – Part 2

Scientific MethodScientific Method

When scientists are thinking and When scientists are thinking and inquiring information to investigate inquiring information to investigate and explain a situation what method and explain a situation what method are they using?are they using?

Scientific Method Scientific Method

What steps does a scientist use in What steps does a scientist use in the scientific method?the scientific method?

Identify the problem – recognize and Identify the problem – recognize and researchresearch

Form a hypothesis – a statement that Form a hypothesis – a statement that can be testedcan be tested

Begin an experiment – they test the Begin an experiment – they test the hypothesis by making predictions hypothesis by making predictions and gathering new data:and gathering new data:

variablevariable

controlcontrol

datadata

Scientists then come up with a Scientists then come up with a conclusion conclusion

Note: this can lead to another Note: this can lead to another hypothesishypothesis

Develop a theoryDevelop a theory

USING SCIENTIFIC METHODUSING SCIENTIFIC METHOD

A biology class raised guppies for a class A biology class raised guppies for a class project. Paula thought the guppies would project. Paula thought the guppies would have more young if the light in the have more young if the light in the aquarium was turned off part of the time. aquarium was turned off part of the time. Other students thought the light should be Other students thought the light should be left on all the time. But, Paula had observed left on all the time. But, Paula had observed that her guppies at home had more young that her guppies at home had more young than the ones at school. She also knew that than the ones at school. She also knew that she kept her aquarium light turned off part she kept her aquarium light turned off part of the time. The class had a problem. What of the time. The class had a problem. What was the problem?was the problem?

The Problem: What should they do about the The Problem: What should they do about the aquarium light?aquarium light?

Paula needed to do some research at the library. Paula needed to do some research at the library. She found out what temperature to keep the She found out what temperature to keep the water and the amount of water needed. water and the amount of water needed. However, there was little information about how However, there was little information about how much light a guppy needs. So what did she much light a guppy needs. So what did she develop at this point?develop at this point?

Answer: HypothesisAnswer: HypothesisPaula’s: “If the light is turned off part of the time, Paula’s: “If the light is turned off part of the time,

then the guppies will have more young.”then the guppies will have more young.”

What is Paula’s next step?What is Paula’s next step?

Answer: test her hypothesisAnswer: test her hypothesisPaula divided 16 guppies into two equal groups. Paula divided 16 guppies into two equal groups.

She put the groups into separate tanks and She put the groups into separate tanks and labeled them group A and group B. She kept the labeled them group A and group B. She kept the temperature in the tanks the same. She put the temperature in the tanks the same. She put the same amount of water in each tank. The light for same amount of water in each tank. The light for group B was left on 24 hours a day. The light for group B was left on 24 hours a day. The light for group A was turned on for 12 hours and off for 12 group A was turned on for 12 hours and off for 12 hours each day.hours each day.

So, what is next?So, what is next?

Answer: Collecting DataAnswer: Collecting Data Paula recorded the number of adult Paula recorded the number of adult

guppies she put into the tank. Once a guppies she put into the tank. Once a week for four weeks, she recorded the week for four weeks, she recorded the number of young produced by each group. number of young produced by each group. She removed the new young each week so She removed the new young each week so she could count more easily.she could count more easily.

What was Paula’s last step?What was Paula’s last step?

Paula’s last step was to conclude whether or not Paula’s last step was to conclude whether or not the problem was solved.the problem was solved.

At the end of the experiment group A had more At the end of the experiment group A had more young than the guppies in group B.young than the guppies in group B.

So, What was the conclusion?So, What was the conclusion?

Answer: Paula concluded that 12 hours of light and Answer: Paula concluded that 12 hours of light and 12 hours of dark caused the difference. She had 12 hours of dark caused the difference. She had determined that the guppies had more young determined that the guppies had more young when they were only exposed to 12 hours of light when they were only exposed to 12 hours of light and 12 hours of darkness.and 12 hours of darkness.