1. Aim: What Experimental design concepts do I absolutely need to know?
Do now: If you have already presented. Write your hypothesis (what you think would happen) for the experiment you designed for the poster.

2. What is the goal of science?
1) The goal of science is to investigate and understand nature, to explain events in nature, and to use those explanations to make useful predictions.

3. What is Science?
Science is an organized way of using evidence to learn about the natural world.

4. Where do we find evidence? “The Scientific Method”
Science starts with observations
Observations involves using one or more of the senses sight, hearing, touch, smell and taste.
Observations (data) can be broken down into 2 types:
a. Quantitative – an observation involving numbers (counting or measurement)
b. Qualitative – observations involving characteristics that are not easily measured (color, texture and size)

6. Interpreting the Evidence
Once the observation is completed and data is collected, the data must be analyzed and interpreted.
The interpretation of an observation is known as an inference.
An inference is a logical interpretation of data based on prior knowledge and experiences.

8. The Hypothesis
A hypothesis is a possible explanation (statement) for a set of observations made by a scientist. It is an answer to a scientific question.
A hypothesis is only valid (truth), when it has been tested through repeated experiments and the results support the hypothesis.

9. The Hypothesis (cont)
A hypothesis may begin with, “I believe… or I think…
There is never a “?” at the end of a hypothesis.
It is a statement, not a question.
Examples:
I believe the Earth is round.
I think more water will help a plant grow taller.
I believe that eating fish will make people smarter.

10. The Experiment
An experiment is a series of tests used to prove the validity (truth worthiness) of a hypothesis. a. Experiments always begin with a question or problem. “Does the amount of sunlight affect a plant’s growth?” b. Once a question or problem is identified, a hypothesis must be formulated. “The plant grows taller with more light .” (a statement)
 Question Mark = Question
No Question Mark (period) = Hypothesis

11. The Experiment (continued)
Experiments must have a control group.
A control group is a group in the experiment that is experimented.
The conditions remain normal and unchanged.
This group is needed to compare the experimental group to. To see if any changes has occurred.
The experiment must have a experimental group. (These are groups that had one thing changed about them.) These groups are having the experiment done to them.

12. What are Variables?
A variable is any factor, trait, or condition that can exist in differing amounts or types.
There are 3 types of variables in an experiment
Independent Variables
Dependent Variables
Controlled variables

13. Independent Variables
The Independent Variable is the condition or item that is changed in an experiment. (THE CAUSE)
Ex: Sunlight makes plants grow.
Ex: If I study then I will get good grades.
I believe that toads cause warts.

14. **An experiment can only test one independent variable at a time!!!!
Example:
Will walking longer distance and chewing gum affect your heart rate?
WRONG!!
Will walking longer distance affect your heart rate?
Will chewing gum affect your heart rate?

15. Dependent Variable
The Dependent Variable is the condition that is affected as the results of the Independent Variable. (THE EFFECT)
Ex: Sunlight makes plants grow.
Ex: If I study then I will get good grades.
Ex: I believe that touching toads causes warts.

16. Controlled variables
All the other variables (excluding the independent) that must remain the same in the experiment.

17. Example 1
The photograph below shows a pill bug. Pill bugs are small animals frequently found in wooded areas near decomposing organic material. A scientist is conducting an experiment to determine the preference of pill bugs for light or darkness.
Design an experiment for the scientist.
In your answer be sure to:
• state the problem
state a hypothesis
• identify the independent variable in
the experiment
• identify two conditions that should
be kept the same in all
experimental setups
• state one example of experimental
data that would support your
hypothesis

18. Example 2
The drugs usually used to treat high blood pressure do not affect blood vessels in the lungs. High pressure in the lungs has a indirect relationship to doing exercise. This means people who have high blood pressure in the lungs tend to get tired quickly during exercise.
Bosentan is a new drug being studied by a pharmaceutical company as a new treatment for high blood pressure in the lungs.
In an experiment, patients treated with Bosentan showed an improvement in the distance they could walk without fatigue (tired) within 12 weeks. While parents not treated with Bosentan show no improvement in their routine walks.
Design an experiment to test the effectiveness of Bosentan as a drug to treat high blood pressure in the lungs. In your answer be sure to:
• state the problem
state the hypothesis your experiment will test
• state how the control group will be treated differently from the experimental group
• state two factors that must be kept the same in both the experimental and control groups
• state the type of data that should be collected to determine if the hypothesis is supported

19. Data
Data is the information collected for the experiment. Usually some kind of measuring.
It is important that the experiment does not get contaminated while collecting data.
Contamination can result in false data readings. Making the experiment inaccurate.
Example – An experiment on how hand sanitizers kill bacteria on hands, can give a false conclusion if the data is collected after some sneezed into their hands.

20. Data Table
The data table is used to help collect and organize the data collected from the experiment.

21. Graphs Sometimes data can be organized into a graph.
A graph is a visual display of data.
Graphs can be used to show comparison between data, trends and predictions.

22. Graphs (continued)
Types of Graphs Pie Graphs- Shows relationship out of 100% Bar Graphs- Shows comparisons between individuals (one variable) Line Graphs- Shows relationship over time (2 variables)

23. Analyzing & Conclusion
After gathering all the data and graphing it. Scientists look for patterns in the graph.
Analyzing means studying and understand what the data is saying.
The conclusion is making an interpretation of what the analyzing process uncovered.
VERY IMPORTANT!!
If the conclusion agrees with your hypothesis than the hypothesis is valid (true)
If the conclusion disagree with your hypothesis than the hypothesis is invalid (not true)

24. How to improve an experiment
Always have a large sample size – the more items tested the more accurate the results.
Make sure the experiment is repeatable – if you cannot repeat the experiment with the same results, than the experiment is invalid.

25. Ethics
12) Many times due to social, economic, and/or personal beliefs, scientist may manipulate data to prove their hypothesis correct even though the results from the experiments prove the hypothesis wrong.

26. Theory
10) A theory is an idea that is supported by valid data and observations. If the experiment was repeated several times, the theory should still hold true.

27. Publication
11) It is important to have the work published. Publication allows others to repeat the experiment. It also gives you credit for the discovery.

28. Assumptions and Opinions
An assumptions is something accepted as true that may or may not actually be true.
A good experiment keeps assumptions to a minimum.
Opinions are ideas people have that may or may not have any basis.
They are often biased or influenced by assumptions.

29. How do you make a line graph?
Example: Does the amount of rainfall affect frog population

30. Why make a line graph?
1) A line graph can e used to show the relationship between your independent and dependent variables after you have collected the data in your experiment

31. How do I know which variables to put on the X and Y axes?
2) The Rules:
The independent variables always goes on the X axis (horizontal)
* The dependent variables always goes on the Y axis (vertical) 

32. What do you mean by label and units?
3. You should label each axis and include the units you measured your variables in.
Example: If you measured one variable in years then you unit is years.

33. What is a scale and does it need to be the same for both axes?
4) You must choose a scale for each box to represent in your graph. This will depend both upon the size of the graph you have been provided and the data you have collected. The scales for your X and Y axes do not need to be the same and you don’t need to start

34. How do I put my Data on the graph?
5)The number you collected and entered on you data table represents the relationship between the two variables. Use the X and Y axes to locate the interception that most closely represent your data and plot it on the graph. Repeat for each piece of data. Once you have plotted all your data, connect them by drawing a line through each plot.

35. How do I make a good title for my graph?
6) A basic formula for a good title is:
“The effect of the amount of rainfall (independent) on the population of frogs (dependent) in Lake Wherever”

36. Lets Design A lab to do in class
The problem: You are opening a new restaurant in your neighborhood called Bio Cafe. You only have room for one soda machine. You want to construct an experiment to find out what your customers like to drink, so that you can install the right machine. You can get 1 of 3 machines: one from Coca Cola, another one from Pepsi or another one from Cheapo Cola Inc. Which would your customers like best?

37. Lets Design A lab to do in class
Rephrase problem:
State your hypothesis:
How would test this hypothesis?
What would be our independent variable?