1. Aim: What Experimental design concepts do I absolutely need to know?
Do now:

2. Review What is Science?

3. 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.

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

5. 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)

7. 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.

9. 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.

10. 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.

11. 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

12. **An experiment can only test one 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?

13. 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.
a. The Independent Variable is the condition or item that is changed in an experiment. (THE CAUSE)
b. The Dependent Variable is the condition that is affected as the results of the Independent Variable. (THE EFFECT)

14. 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

15. 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