The Scientific Method In Depth. Step 1 - Observations Use your senses: sight, smell, hearing, touch,...

The Scientific Method

In Depth

Step 1 - Observations

Use your senses: sight, smell, hearing, touch, and taste

Example: I noticed I have to fill up my gas tank sooner when my tire pressure is low.

Example: I noticed that my bird seems to play more with toys that are the same color she is (red and yellow)

Writing Observations

Come up with three observations on your own

1.

2.

3.

Step 2 - Problems/Questions

What are you trying to solve?

Must be written in “HOW DOES the IV AFFECT the DV” format

Example: HOW DOES tire pressure AFFECT gas mileage?

Example: HOW DOES the color of a toy AFFECT how much my bird plays with the toy?

Writing Problems/Questions

Write three problems/questions to go along with the observations you made.

1.

2.

3.

Ste 3 - Hypotheses

Review: – It must be testable– It may or may not be correct– It is a possible answer or solution

It makes a prediction about the outcome of the experiment

Must be in written in “IF_________, THEN________” format

Hypotheses Continued

Example: IF tire pressure is low, THEN the gas mileage of the car will decrease.

Example: IF I give my bird the same toy in several different colors, THEN she will spend more time playing with the toys that are red and yellow.

Writing Hypotheses

Write three hypotheses to go along with the observations and problems/questions you made earlier

1.

2.

3.

Variables

Independent Variable– The one we change – Can be thought of as “the cause”

Dependent Variable– “Depends” on the independent variable– Can be thought of as “the result”

Controlled Variables– Variables that do not change

Variables Cont.

Example:– Independent Variable: tire pressure– Dependent Variable: gas mileage– Controlled Variables: tire size, highway or city driving,

temperature

Example:– Independent Variable: toy color– Dependent Variable: time spent playing with red and yellow

toys– Controlled Variables: type of toy, placement of toy, time of

day

Identifying Variables

Write the independent, dependent, and at least 3 controlled variables for your previous hypotheses

1.

2.

3.

Step 4 - Experiment

Check for safe and ethical procedures

ID Materials Needed

Design a Protocol (Procedure)– Should be step by step– Make it so clear and simple a 1st grader could do it

DO IT!

Lab Safety

What is lab safety?

– Properly handling hazardous situations and conducting yourself in a responsible manner at all times in the laboratory

Safety

Wear protective clothing– Goggles, gloves, lab coat, closed-toed shoes

Read and follow directions carefully Use extreme caution around chemicals or flames Be careful when handling glassware Never run or mess around in the lab Clean up and wash your hands after every experiment Notify your teacher IMMEDIATELY if any problems

arise

Ethics

Never “make up” data

Treat all subjects (people and animals) with respect

Minimize risks and harm

Safety and Ethics Quiz!

What would you do in these situations using good lab safety behavior?

1. Disposing motor oil from a car engine must be done in a legal and safe manner. Which of the following would be the most ethical procedure to dispose of motor oil?

a. Place oil in a waste management container b. Pour oil down the drain

c. Take to a local disposal stationd. Place in recycling container

During an experiment a glass container falls to the ground and breaks. What is the proper lab safety procedure for cleaning up broken glass?

a. Pick up glass pieces off the floor and place in trash container.b. Inform lab instructor immediately and wait for directions.c. Begin picking up glass pieces off the floor while informing lab instructor.d. Find the nearest broom and sweep pieces of glass into trash container.

When handling chemicals in a laboratory setting, what is the appropriate safety equipment that should be worn?

a. goggles, rubberized gloves, rubberized apron and closed toed shoesb. goggles, cloth gloves, cloth apron and closed toed shoesc. goggles, rubberized gloves, cloth apron and closed toed shoes d. goggles, rubberized gloves, rubberized apron and open toed shoes

During an experiment to collect data for medication

effectiveness what is the ethical procedure for collecting this data?

a. all data collected when needed and recorded at random times.b. some data collected and accurately recorded.c. some data collected in a timely manner and recorded.d. all data collected in a timely manner and accurately recorded.

What is the proper disposal procedure of laboratory animal waste?

a. Clean up area often with sanitary product and bag solid waste.

b. Clean whenever time permits and put into trash container.c. Place waste in a trash container and clean weekly.d. Place solid waste in a bag and use sanitary product

when needed.

Lab Equipment

See Notebook File

Step 5 - Data Collection/Analysis

Sketches Pie Charts Bar graphs Line graphs Scatter Plots

Data Collection - Sketches

Sometimes it is appropriate to sketch the lab equipment set up or the results of the experiment.

Data Collection - Pie Charts

Represents parts of a whole

– Find the percentage (out of 100%) for each data set

Data Collection - Pie Charts

Mexico

$8136 = 27.62 %$29460

Data Collection - Bar Graphs

Used when you have qualitative (no numbers) data

Data Collection - Line Graphs

Show how two things are related and how they change depending on each other

– Dots can be connected or a Best Fit Line can be used– Use same formatting we learned during graphing

Data Collection - Line Graphs cont.

Data Collection - Scatter plots

Show how two things are related and how they change depending on each other– Multiple sets of data for each increment– Dots are not connected – Use a Best Fit Line– Same formatting we learned during graphing

Data Collection - Scatter Plot cont.

Positive – Both the independent and dependent variables are increasing

Data Analysis – Types of Relationships

Data Analysis – Types of Relationships

Data Analysis – Types of Relationships cont.

Negative – one variable is increasing and the other variable is decreasing

Data Analysis – Types of Relationships cont.

Data Analysis – Types of Relationships cont.

No Relationship – one variable is increasing while the other variable is increasing AND decreasing

Data Analysis – Types of Relationships cont.

Data Analysis – Types of Relationships cont.

Stationary – one variable is increasing while the other variable stays the same

Analyzing Data – Descriptive Statistics

Mean – the AVERAGE of a set of data– Add all the values and divide by the total number

of values– Example: 2, 8, 6, 7, 2

1. Add together = 25

2. Divide by 5 = 5

3. Mean = 5

Analyzing Data – Descriptive Statistics

Median – the MIDDLE value when the values are put in order– Example (odd number of values): 2, 8, 6, 7, 2

1. Put values in order = 2, 2, 6, 7, 8

2. Find the number in the middle

= 2, 2, 6, 7, 8 3. Median

= 6

– Example (even number of values): 3, 2, 4, 5, 2, 1 1. Put the values in order

= 1, 2, 2, 3, 4, 5 2. Find the middle number

= 1, 2, 2, 3, 4, 5 3. Find the average

= 2+3 = 2.5

2 4. Median

= 2.5

Analyzing Data – Descriptive Statistics

Mode –the value that appears the most often– Example: 2, 8, 6, 7, 2

1. Find the number that appears the most

=2 2. Mode

= 2

Analyzing Data – Descriptive Statistics

Range - a measure of how the data is spread out. – Subtract the smallest number from the largest number. – Example: 2, 8, 6, 7, 2

1. Smallest Number = 2

2. Biggest Number

= 8 3. Subtract

= 6 4. Range

= 6

Analyzing Data – Descriptive Statistics

Frequency – how often each value appears in a set of data

– Often shown in a frequency table

– Example: 2, 8, 6, 7, 2

Value Frequency (# of time it appears)

2 2

6 1

7 1

8 1

Step 6: Conclusion

In a conclusion, you must include the following:– Restate your hypothesis and whether or not the data

supported it (were you right or wrong?)

– State the effect of the IV on the DV Ex. As the IV increased, the DV decreased

– State the relationship between the IV and DV Ex. Negative relationship

– Use ACTUAL DATA to support your conclusion

Conclusion cont.

Recommendations– What new questions do you have?

– What would you change for the next experiment? What were the strengths and weaknesses of the

experiment?

Step 7: Evaluation

Check for:– Appropriate sample size– Appropriate number of trials– Clearly defined variables– Control group (when applicable)

Used for making comparisons

– Controlled variables Make sure nothing but the IV and DV changed in the

experiment