Experimental Design

Experimental Design

Scientific MethodIntro Chapter

P 6-7

Scientific MethodIntro Chapter

P 6-7

• Different ways that scientists investigate problems and find answers.

What is Scientific Inquiry?

• What is the very first thing one must do in order to learn anything?

– 1. State the problem.• ___________ a question.

Scientific Method

• Step 1 Materials- Using the materials on your desk, write a problem.

Scientific Method

• Step 2. Hypothesis- a _____________ statement.

• Create a hypothesis for your problem.

Scientific Method

• Step 3 Design Experiment– Variable Worksheet

– Independent Variable is the variable that is __________________.

• I CAN CHANGE IT.

• The independent variable is ______________.

Scientific Method

• Step 3 Design Experiment

– Dependent Variable is the variable that is __________________ by the independent variable.

– Dependent variable is __________________.

Scientific Method

• Step 3 Design Experiment

– Constants- are factors we want to keep the same.

• Helps scientists know that the independent variable is causing the change.

Scientific Method

• Step 3 Design Experiment– Control- serves as a ______________ for

the scientists.• Example:

– Placebo- when testing medicine.» One group gets the meds.» One group gets the placebo (usually a sugar pill).» Was there any change due to the drug?

• Control for the Ice Experiment?

__________________________

Scientific Method

• What does it mean to make observations?

• What might you be looking for in this experiment?

Observations

• What do you know based on previous knowledge?

Inferences

• The standard system of measurement used by scientists around the world is known as the International System of Units. (SI System)

What is the Metric System?

• Based on multiples of 10.

= 1000

= 100

= 10

0.1=

0.01=

0.001=

= 1

What is the Metric System?

• Distance between two points.

• Tool used: Meter Stick or Metric Ruler

• Unit = cm- centimeters

Length

• Distances– cm or mm= small distances.– m= short distances– km= distance between cities.

Length

Volume

• The amount of space an object contains or takes up.– Liquid Volume-

Meniscus line = curve of liquid

• Graduated Cylinder– Unit = milliliter (mL)

Volume

• The amount of space an object contains or takes up.– Solids-

• L*W*H– Unit = centimeter cubed (cm3 )

Volume

• The amount of space an object contains or takes up.– Irregular Solids-

• Water Displacement

– cm3 = mL

• The amount of matter in an object.

Mass

Mass

• Mass is constant, – which means it is always the same.

• Tool used- Balance– Measured in grams (g)

Mass

• Practice reading the balance below:

Control

Independent Variable

Dependent Variable

9.51

0.1 g

10.18

1.2 g

21.28

Group A

10.09

0.2 g

10.31

1.1 g

24.09

Group B

9.41

0.3 g

11.20

1.0 g

15.59

Group C

9.46

0.4 g

12.00

0.9 g

18.32

Group D

10.15

0.5 g

12.30

0.8 g

18.45

Group E

11.35

0.6 g

19.05

0.7 g

19.20

Group F

Data Table

• A useful way to summarize your data.

– Elements of a good graph• Neatly constructed (use a

straight edge)

• Use the entire sheet of graph paper.

• Create a scale for the x and y axis.

• Label the axis

• Title your graph.

• Provide a key if needed.

Graphing Data

Graphing Data

• A well tested scientific concept that explains a wide range of observations.

– Big Bang Theory• Enough evidence

supports this theory.

What is Scientific Theory?

• They are generalizations about how the natural world behaves under certain conditions.

• Example:– Has an object ever fallen

up?• The law of gravitation.

What is Scientific Law?

• Conclusion- Explain what happened? (Do not use first or third person in your written conclusion- personal pronouns, no I or we in the conclusion)– Restate the problem that was investigated. (circle in the

example)

– State what the hypothesis was. (underline)

– Explain what the results showed. (Box in)

– Did the results support of disprove the hypothesis? (draw a star)

– List any questions this data now leads you to? (Explain find out the answer to your question.) (lightly shade)

Conclusion

• The problem investigated was to see how aspirin affected the growth of a cut flower. The hypothesis that aspirin in the water of cut carnations would help the flowers last longer was not supported by the data. As the amount of aspirin was increased in the water, the flowers died faster. The control of the flower that did not have any aspirin in the water lasted the longest. From this data the conclusion would have to be that aspirin does not help the carnation last longer. However, this does bring up the question, what is it in aspirin that kills the flowers so fast?

Example Conclusion

Water / Salt Water Results