Upload
pauline-casey
View
215
Download
0
Tags:
Embed Size (px)
Citation preview
• 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.