October 14, 2010

1) If you have not handed in your $5 and Biobus form, please do so on Monday during Advisory.

2)Making Connections Lab: Write a first draft of your report in your sourcebook using the guidelines on the last page of the lab packet (see below for guidelines). This must be fully ready in order to collect data.

Guidelines for Designing a Controlled Experiment

Scientist follow certain guidelines when they conduct and report on a controlled experiment. These are provided below. As you work through this section to design your experiment, make notes as you go along. Your notes will become the outline for your investigation, and you can use them to prepare a final version at the end.

1. Determine the question you are trying to answer. The question should be directly related to what you want to find out. For example, if you want to know whether or not light intensity affects tomato seed germination (the emergence of a plant from the seed), you might ask, “Does light intensity affect tomato seed germination?” Write in your notes the question you will be attempting to answer.

2. Formulate the hypothesis you will be testing with your experiment. The hypothesis is a tentative statement about the expected relationship between the variables. This statement must be written in a way that allows the relationship to be tested. If often suggests that there is a connection between two factors. For example, “Light intensity will influence the germination of tomato seeds.” Write in your notes the hypothesis you will be testing.

3. Formulate a title for your investigation. A title addresses specifically what is being investigated. The title should be a statement in the form of “The effect of …..on…” You should specify the organism(s) you are using as well. For example, “The effect of light intensity on seed germination in tomato plants.” Write the title of your experiment in your notes.

4. Plan the design of your experiment. In the planning of your experiment, consider each of the following. Make notes of your ideas to use later.
a. You need to decide what data you will collect. The dependent variable is the one you measure. In this investigation, the number of times the clothespin can be squeezed in a minute is the dependent variable.
b. What is to be you independent variable – the one you will vary to see how it may affect the dependent variable? In this investigation, you might make the independent variable the subject’s level of activity just before each of the trials during which you measure that subject’s clothespin-squeezing rate.
c. To do a fair test (controlled experiment) and obtain a valid conclusion, you must keep all but the independent variable constant. What other variables will it be important to keep constant to obtain meaningful data? What is your control?
d. Decide how many individuals you will test, how many trials you will conduct with each, and the conditions to which they will be subjected. In this case, you need to determine how many people you will test and what you will have them do.
e. Make note of safety precautions that will be necessary.

Write out the steps of your experimental design in your notes.

5. Design one or more data tables that you will use to record the data as it is collected. Your data table(s) should also have sections for summarizing or averaging the data, as appropriate. Your data table(s) must be designed and finalized before you begin the experiment. Sketch in your notes the data table(s) you plan to use. Be sure to include appropriate headings and units.

6. Write out the steps you will follow to conduct your experiment.