1. Experimental design: Review
For each of the following experiments, describe the constants, control, and variables…

2. Experiment 1
Scientists wanted to see whether Ginko Boa, a medicinal herb, actually improved memory and neurological activity. They performed a double blind study, giving one half of the 500 participants Ginko Boa, and the other half a placebo. Participants were to take their pill at the same time each day. Other factors were kept the same as well: exercise, diet and daily routines. As a result of this study, it was found that there was no significant change in retention or memory in either group.

3. Answer the following:
What is a possible hypothesis for the given problem in this study?
State the control:
Which variable is dependant?
Which variable is independent?
What was the conclusion to this experiment?
How could scientists be sure their conclusion was accurate?

4. Experiment 2
Scientists wanted to know what would happen if the pH of the water in a pond would affect the growth of certain algae. They collected 20 samples of pond water in 10 gallon tanks. Then, keeping the light, temperature and number of organisms the same, they altered the pH. They conducted the study for a 3 week trial period. These are some of their results:

5. Results: Tank A: pH=7, steady algae growth
Tank B: pH=11, rapid decline in algae growth
Tank C=5, growth at a constant rate
Tank D: pH=1, rapid decline in algae growth

6. Answer the following:
What is a possible hypothesis for this experiment?
Which variable is dependant? Independent?
What are the constants?
What is the control?
How would the data be graphed?
What would you conclude for this experiment?