The Scientific Method

The Scientific Method

The Question

• A Scientific Question can be answered by gathering scientific evidence (with measurements / observations) – testable & measurable– Do not use term – better? How is that measured?

• An example of a scientific question is “Which freezes faster—fresh water or salt water?”

RESEARCH“Review of Literature”

Before you can begin your investigation, you must find out all the information you can that is known about your topic.

Use •textbooks and science books•Science journals (usually high level)•Internet resources -- (.edu or .gov)•You must pay attention to the source

•Is the source bias?•Is the source accurate?

The Hypothesis• Developing a hypothesis - give possible outcomes

for the tested variables. It is based on research & previous knowledge and observations.

• MUST be If…Then.• The “If” states what variables are being tested.• The “then” part of the hypothesis must be

collectable data.•  An example of a hypothesis is “If fresh water and

salt water are frozen, then the salt water will take longer to freeze.”

Rationale

• Explain why the hypothesis is correct based on the review of the literature.

Adding salt to water lowers the freezing point of water. This will cause salt water to take longer to freeze.

The Procedure (Experiment)• The Experiment is a plan to test your hypothesis. • It should be a detailed, step-by-step list of procedures and should

describe the observations or measurements to be recorded. • The control, dependent variable, independent variable, and constants need to be

identified.

An example of a procedure:1. Label two, 500 mL containers with numbers 1 and 22. Fill the two 500 mL containers with 300 mL of fresh water3. Add 10 g of salt in container # 1 4. Place the 2 containers in the freezer5. Check the containers every 15 minutes and record your observations. 6. Record the time it took for the water to freeze.7. Repeat steps 1-6 five times.

Variable(s) • Variable: Any factor that can change in the

experiment• Independent Variable: A factor that is manipulated

or changed (on purpose)• Dependent Variable: Factor that is measured /

observed / or recorded• Control: The independent variable that is the

“normal” condition• Constants: variables that are kept the same for all

groups

Let’s Practice Variables• List all variables that may affect our experiment,“Which freezes faster—fresh water or salt water?”

Variables that may affect the experiment.

• Type of water• Amount of water • Temperature of water• Type of salt• Amount of salt• Position in freezer• Type and size of freezer

• Temperature of freezer

• Container used• How close containers are

to other objects• How often the freezer

door is opened

Let’s Identify the following:

• Independent Variable

• Control

• Dependent Variable

• Constants

Answers on next slide

Identify the following

Constants:• Type of water• Amount of water • Temperature of water• Type of salt• Position in freezer• Type and size of freezer

• Temperature of freezer• Container used• How close containers are to

other objects• How often the freezer door

is opened

Independent Variable: Amount of salt

Control: Freshwater (zero salt)

Dependent Variable: Time it takes to freeze

DATA COLLECTIONData must be collected in a table.BEFORE experiment is done, you must have a data table.Use the header row of the table to list the units, do not list the units in each box.

Time Elapses

(min)

Freshwater Saltwater

0

15

30

45

Interpreting Data

• Interpreting data means analyzing the information collected during the experiment looking for patterns or trends (relationships) • This is best done by organizing your data into

GRAPHS.

The Conclusion

• You need to state whether or not the data supports or does not support the hypothesis.

• Restate your data (use averages).

The Discussion

Write about what you have learned from the experiment. - why did you get the results you did- evaluate your data- relate research to findings- real-life application of results- possible sources of error - ways to improve your project- ideas of further research

Let’s Practice

Will house plants grow faster if you make the room warmer?

1. Variables that could affect the results:

2. Independent variable:

3. Dependent Variable:

4. Variables to be kept the same -- aka “Constants”

5. Control

6. Write a hypothesis.

7. Write a rationale.

Possible Answers:1. Variables that could affect the results:

Temperature, plants, soil type, amount of soil, containers, water, light, plant food

2.  Independent variable: Temperature the plants are kept

3.  Dependent Variable: Height of plant (growth) (You could also measure weight as an indicator of growth)

4. Variables to be kept the same: ConstantsSame kind of plant, same type and amount of soil, identical containers, same amount of water, same amount of light, same amount of food

5. Control: Room Temperature

6. Hypothesis: If house plants are grown in different room temperatures (15 oC, 25 oC, and 35 oC) then the plants grown in 35 oC will grow the fastest.

7. Rationale: The temperature affects the rate of chemical reactions. Because the rate of chemical reactions increases with temperature, the plant will grow faster in the higher temperature.

Answer for these two Questions:Question 1: Does fertilizer make a plant grow taller?

Question 2: Is studying in a quiet place better than studying in a noisy place?

1. Variables that could affect the results:

2. Independent variable:

3. Dependent Variable:

4. Constants (variables to be kept the same)

5. Control

6. Write a hypothesis.

7. Write a rationale.

Does fertilizer make a plant grow taller?

1. Variables that could affect the results:

2. Independent variable:

3. Dependent Variable:

4. Constants (variables to be kept the same)

5. Control

6. Write a hypothesis.

7. Write a rationale.

Possible Answers: Does fertilizer make a plant grow taller?1. Variables that could affect the results:

Temperature, plants, soil type, amount of soil, containers, water, light, plant food

2.  Independent variable: Amount of fertilizer measured in grams

3.  Dependent Variable: Growth of the plant measured by its height in centimeters

4. Variables to be kept the same: ConstantsSame kind of plant, same type and amount of soil, identical containers, same amount of water, same amount of light, same temperature, same placement of seeds in soil

Possible Answers: Does fertilizer make a plant grow taller?

5. Control: No Fertilizer

6. Hypothesis: If a plant is grown with different amounts of fertilizers, then the plant that received the most fertilizer will grow the tallest.

7. Rationale: Fertilizer provides more nutrients for the plant to grow.

.

Is studying in a quiet place better than studying in a noisy place?

1. Variables that could affect the results:

2. Independent variable:

3. Dependent Variable:

4. Constants (variables to be kept the same)

5. Control

6. Write a hypothesis.

7. Write a rationale.

Possible Answers: Is studying in a quiet place better than studying in a noisy place?

1. Variables that could affect the results:participant prior knowledge, age or participant, subject of test, number and type of questions, type of test (oral / written), time allowed for test, noise level, directions given…

2.  Independent variable: Quiet study place or a noisy study place

3.  Dependent Variable: Grade on quiz

4. Variables to be kept the same: ConstantsUse only 6th grade students, same types of reading (for studying) and same type of questions on tests, same number of questions, same time allowed for test, same directions given…

Possible Answers: Is studying in a quiet place better than studying in a noisy place?

5. Control: Quiet place

6. Hypothesis: If students study for a quiz in a quiet or noisy environment, then the students that studied in a quiet environment will get a higher grade on the quiz.

7. Rationale: It is easier to concentrate in a quiet area.

Experiment 1Helen thinks that a special juice will increase the productivity of

workers. She creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, The stacks of stapled papers is counted. Group A made 1,587 stacks, Group B made 2,113 stacks.

Identify the:1. Control Group:2. Independent Variable:3. Dependent Variable:4. What should the conclusion be? 5. How could this experiment be improved?

Experiment 2Bob notices that his shower is covered in a strange green slime. His

friend tells him that coconut juice will get rid of the green slime. Bob decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of "treatment" there is no change in the appearance of the green slime on either side of the shower.

Identify the-1. What was the initial observation? 2. Control Group:3. Independent Variable:4. Dependent Variable:5. What should the conclusion be?

Experiment 3Sam was told that a certain itching powder was the newest best thing

on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes.

Identify the-1. Control Group:2. Independent Variable:3. Dependent Variable:4. Does the data support the advertisements claims?5. How could this experiment be improved?

Making A+ GraphsS.U.L.T.A.N. C

• S = Scale - numbering axes, spreading out data

• U = Units - What type of numbers are recorded

• L = Labels - What the data is measuring

• T = Title - Scientific and descriptive

• A = Accuracy - Plot points correctly

• N = Neatness - Use a ruler!

• C = Caption - Explain the graph

Identify the title, label, scale, and units

Does a plant that gets more sunlight grow faster?

1. Amount of exposure to sunlight measured in hours2. Growth of the plant measured by its height in

centimeters3. If plants get different amounts of sunlight, then the

plant with the most sunlight will grow the tallest.4. Plants require sunlight for photosynthesis, which

provides the plant with food and energy needed for growth.