the steps that scientists take to gather information and answer questions

• The steps that scientists take to gather information and answer questions

1) Identify problem/Ask question

2) Conduct Research

3) Formulate a hypothesis

4) Experiment

5) Analyze results and make a conclusion

6) Retest if necessary

• Asks a question

• What are you trying to solve?

• What is it that you want to know?

• Use the following:– Books– Magazines– Reports– Experts– Your past

experiences

• Testable explanation for a question or problem

• Example: Tomato plants will show an increased growth rate when planted with a greater amount of fertilizer

• Null Hypothesis (H0):

– Hypothesis of no difference or no effect

– Example: Tomato plants will show no difference in growth rate when increasing the amount of fertilizer. If results are statistically significant, the null hypothesis can be rejected

• Plan the design of your Experiment.

• Consider the following………

• Three Types of Variables1. Independent

2. Dependent

3. Controlled (constants)

2. Dependent variable– Variable that responds

to changes in the independent variable

– What is measured (data)

– “Depends on” the independent variable

– Plant growth (cm)

3. Controlled Variables (AKA Constants) :– Factors that are kept the same

– Ex. Species of tomato, amount of sunlight, amount of water, etc.

Must keep all other variables controlled,

so any changes seen are the result of the independent variable

Independent & Dependent Variables

• independent variable is plotted on the x-axis• dependent variable on the or the y-axis

inde

pend

ent

dependent

• An Experimental Group will be the group with the Independent Variable:

• In this example, the plants receiving the various amount of fertilizer.

• A Control Group is identical to the experimental group but without the Independent Variable

• In this example, they wouldn’t receive the fertilizer.

• A Control group is for Comparison.

• Make a data table

• Label the sections of your table.

• Always put in the correct units given or being used

# of Days Height of plant (0g fertilizer)

Height of plant (50g fertilizer)

Height of plant (100g fertilizer)

2 3 cm 6 5

4 6 cm 11 9

6 10 cm 18 13

• Create a table, chart, or graph for numerical data

• Take data and use it for

• Summary of what you found when you tested your hypothesis– Use DATA to support conclusion

• Was your hypothesis supported?

• What could have/did go wrong?– Things that could have caused

abnormal results

– Called sources of error

Lets put our knowledge of the Scientific

Method to a realistic example that includes

some of the terms you’ll be needing to use and understand.

John watches his grandmother bake bread. He ask his grandmother what makes the bread

rise.She explains that

yeast releases a gas as it feeds on sugar.

John wonders if the amount of sugar used in the recipe will affect the size of the bread

loaf?

John researches the areas of baking and

fermentation and tries to come up with a way

to test his question.

He keeps all of his information on this topic in a journal.

After talking with his teacher and

conducting further research, he comes up with a hypothesis.

“If more sugar is added, then the bread will rise

higher.”

Do you know the Do you know the difference between the difference between the

independent and independent and dependent variables?dependent variables?

The independent, or manipulated variable, is a factor that’s intentionally varied by the

experimenter.John is going to use 25g., 50g.,

100g., 250g., 500g. of sugar in his experiment.

The dependent, or responding variable, is the factor that may change as a result of changes

made in the independent variable.

In this case, it would be the size of the loaf of bread.

His teacher helps him come up with a

procedure and list of needed materials.

She discusses with John how to

determine the control group.

Because his grandmother always used 50g. of sugar in

her recipe, John is going to use that amount in his control

group.

John’s teacher reminds him to keep all other factors the same so that

any observed changes in the bread can be attributed to the

variation in the amount of sugar.

These factors are called constants

Can you think of some Can you think of some constants for this constants for this

experiment?experiment?

• Other ingredients • Type of oven• Rising time• Brands of ingredients• Cooking time• Type of pan used• Oven temperature• Age of yeast• ETC…

John writes out his procedure along with a materials

list in his journal.

Trials refer to replicate groups that are

exposed to the same conditions in an

experiment.

John is going to test each sugar variable 3

times.

John gets all his materials together and carries out his

experiment.

Amt. of Sugar (g.)

1 2 3 AverageAverage

Size (cmSize (cm33))

25 768 744 761 758

50 1296 1188 1296 1260

100 1188 1080 1080 1116

250 672 576 588 612

500 432 504 360 432

Size of Bread Loaf (cmSize of Bread Loaf (cm33))

TrialsTrials

Control group

John examines his data and notices that his control

worked the best in this experiment,

but not significantly better than 100g.

of sugar.

John rejects his hypothesis, but

decides to re-test using sugar

amounts between 50g. and 100g.

Once again, John gathers his materials and carries out his

experiment.

Here are the results.

Amt. of Sugar (g.)

1 2 3 AverageAverage

Size (cmSize (cm33))

50 1296 1440 1296 1344

60 1404 1296 1440 1380

70 1638 1638 1560 1612

80 1404 1296 1296 1332

90 1080 1200 972 1084

Size of Bread Loaf (cmSize of Bread Loaf (cm33))

TrialsTrials

Control group

John finds that 70g. of sugar produces the largest loaf.

His hypothesis is accepted.

Ms. Webb wants to know if a new brand of sneakers can help our cheerleaders jump higher as they cheer on the Eagles. She gave out new Nikes, Adidas, or Reeboks to most of the girls and the rest of the squad wore the old, non-name brand sneakers. Then she measured each girl’s jump height and took the average for each shoe type.

Shoe Type Average Jump Height

Nike 10 inches

Adidas 7 inches

Reeboks 7 inches

Non-name brand 5 inches

Practice Problem #1

A study was designed to determine if a chemical called antirosa prevents conjunctivitis (pink eye). 10,000 individuals were divided into four groups. Each person took a pink pill every morning for one year. Some patients received 3 grams of antirosa, some received 6 grams of antirosa, some received 9g of antirosa and some received a sugar pill. Then the number of times patients developed conjunctivitis was measured

• A scientist conducted an experiment to test whether maple seeds exposed to acid rain will take longer to grow than seeds exposed to normal rain. The scientist set up four groups. The water used for each group had a different pH value: 5.6, 4.0, 3.0, and 2.0. Normal rain has a pH of 5.6 and acid rain has a pH between 1.5 and 5.0. After ten days, the number of seeds that had germinated (grown) in each group was counted.