Fall2011_Lab13

=Lab 13 -- Experimental design (create and perform your own experiment)=

This week we will be working in groups to perform the last lab. This lab will continue into next week, but only until Monday. Monday will be the last day of classes for the lab. The last lab will basically be creating an experiment in groups of 3-4.

Monday: Work in groups to create a hypothesis and write up the entire workflow for the experiment. This will be done in class, as a group, and it will be worth 20 points.

Wed: Conduct the experiment, gather data, begin to write up a 3-5 minute presentation of the experiment. Participation in the experiment (including the first 15 minutes of class) will be worth 7 points of the worksheet 13 grade, and also worth 7 points from the presentation grade (presentation on Wed).

We'll also have one last quiz, and this quiz will be for quiz 11 and quiz 12, worth 10 points each. Quiz 11 will be over the last week of community ecology stuff (see Lab 12 "notes for 2nd week"), and quiz 12 will be over the concepts covered this Monday (experimental design and hypothesis testing). The notes will be on the class website.

Monday (Dec. 5th): Each group will present their experiment and their results. Your lab book gives you guidelines, and I'll go over what is expected for the presentation this coming monday. This is worth 20 points.

Experimental design:
For Wednesday, you must have the experiment up and running by 15 minutes after class has started. This experiment should run 60 minutes, and you need 15 minutes to shut the experiment down and clean up. This leaves 20 minutes to collect data. The hardest part will be setting up the experiment in 15 minutes

On Monday, you will have to write out in detail the experiment, with lots of detail as to who does what, and when they do it. This includes making the solutions, the arrangements of the test tubes, and who cleans up what. It will also include the details of each procedure, as to what gets mixes, and the steps you will take to make the final mixture. There is easy and hard ways to do the experiment, and if you do it the hard way you may not have your experiment up and running in 15 minutes.

Each group will write up all the details of the experiment during class on Monday, and go over it with me, and make corrections until it is good. When it is 'good' this means you will have all the necessary information, and you'll get full credit for the worksheet (assuming you do the experiment on Wed.). So it's an easy 20 points.

Notes:
- How are controls necessary to know what is going on during your experiment? What if your experiment had no controls? Imagine I am testing whether yeast growth depends on how much alcohol is present. My control would be a setup with no alcohol present. If I only tested the yeast with different amount of alcohol, over 60 minutes, I would not know what my baseline growth for 60 minutes would be. So then I would not know how much more or less the growth would be when the alcohol is present. This is a negative control. A positive control accounts for the same thing, but it sets a baseline for maximum growth. If alcohol helped yeast grow, then a positive control would be a setup where there is enough alcohol to give the maximum growth. - When you come up with a hypothesis, this should tell you what your independent and dependent variables are. - After your group came up with a hypothesis, it had to create the experiment itself. Why didn't you use only one test tube for each setup? You use 3-4 tubes per setup, and this replication helps to make sure that any errors that creep into your experiment (maybe you poured something wrong, maybe one of the tubes was dirty), that the error in one part of a setup does not throw off the entire experiment. How do you analyze your data after you collect all the information about the yeast growth (you'll measure the gas in the tube with a ruler)? You'll have to figure out how to come up with a single number for each setup, even though you have 3-4 tubes per setup.

Presentation:
Read the rubric on p. 183 for all of the things you need in your presentation. The Project Rubric part will be the things you should present. The presentation should be about 5 minutes per group. The presentation should be split evenly between all the group members. Materials in the rubric includes the chemicals and types of experimental setup that you used. What did you use to test your hypothesis? The Discussion and Conclusion should have you comparing your results to your hypothesis. What does your hypothesis predict? What did you see in the end? Compare and contrast, and give you explanation for why your results did or did not agree with your prediction.