Statistical Test 

I used averages to compare all of the trials, and make an accurate generalization to compare to my hypotheses. 

Control: 5+3+4= 12/3= 4cm 

Sunlight: 13+9+17= 39/3= 13cm

Shade: 6+5+11= 22/3= 7.33cm

Analysis 

My data supported my experimental hypothesis and refuted my null hypothesis. The data shows that the earthworms crawled the farthest distance when originally placed in the sunlight with the shaded end present. The average distance crawled was greater in the shade then the control but the earthworms did stay in the shade never leaving the edges of shade. The earthworms in the control stage were unmotivated to do anything. since the earthworms in the shade were active but not making a mad dash for the other end, it is reasonable the conclude that they prefer the shady, darker environments to sunny, bright ones. 

Conclusion 

My experiment proved that earthworms prefer shady environments to sunny ones. This finding make sense when one looks at where the earthworms live, in the soil. It also offers insights into the Darwinian theory of natural selection.The earthworms main predator is the bird and birds spend most of their time above ground in the sunlight. The fact that the earthworms evolved in such a way as to prefer the deep dark soil, would keep them away from the birds and safer. This is exactly Darwin's theory, that organisms that adapt to survive, live long enough to pass those life saving skills on to their offspring. That is a reason the earthworms prefer the dark.    

Data Graphs

Couldn't figure out how to upload so see attachments in e-mail.

Data 

Qualitative Data

 

	Control	Sunlight	Shade
Earthworm #1	Worm crawled randomly around not headed in any particular direction	Worm crawled toward the opposite end of the pan	Worm crawled haphazardly around
Earthworm #2	Worm crawled randomly around not headed in any particular direction	Worm zigzagged a little but crawled to the opposite end of the pan	Worm crawled to edge of shade then came back
Earthworm #3	Worm crawled randomly around not headed in any particular direction	Worn crawled almost in strait line to the opposite end	Worm crawled to edge of shade and around it

Quantitative Data 

	Control	Sunlight	Shade
Earthworm #1	5cm	13cm	6cm
Earthworm #2	3cm	9cm	5cm
Earthworm #3	4cm	17cm	11cm

Procedure

1. Set up  both apparatuses (Line pan/tray with damp paper towels and cover with soil)
2. Place earthworms in one pan until you are ready to begin testing (this will be their home pan) 
3.  Take the first worm, place it in the testing pan, mark where you placed it and immediately begin timing
4. After a minute mark where the worm ended up and measure the vertical distance (this is your control)
5.   Then, create the testing apparatus by taping the dark paper to one side of the tray (so that it is covering about half of it)
6. Set the earthworm on the bright side of the pan and repeat steps 3-4
7. Set the earthworms on the opposite side of the tray under the shaded region and again repeat steps3-4
8. Repeat steps 3-7 for other two worms  

Materials 

http://science.discovery.com/tv/head-rush/science-experiments/worms-light-experiment-02.html

1. Earthworms (look in soil in your yard or anywhere)
2. A couple scoops full of soil (as much as you need to cover the bottom, so that the worms can crawl around but not enough so that you will lose them)
3. Two aluminum tins or trays (one to hold worms and one to test in)
4. Paper towels 
5. Thick black paper to block light
6. Scotch tape 
7. Cup you can fill with water 
8. Either a small table lamp or sunlight
9. Tape measure and Ruler
10. Timer     

Repeated Trials 

The experiment was conducted three times, the reason for the repeated trials was to insure that the data was reliable. Although we cannot completely eliminate human error and the possibility of false positives with faulty trials, the presence of repeated trials reduces the likelihood of either of those. 

Test Subjects 

I used three different earthworms (one for each trial). It is important to use multiple test subjects to make sure your hypothesis is true for the whole group you are testing and not just your individual subject.       

Variables and Constants

Independent Variable: Amount of light earthworms are exposed to (manipulated variable)

Dependent Variable: Distance crawled towards opposite end of apparatus (responding variable)

Control: earthworm in pan without differing amounts of light (no shady side all neutral light)  (The control is the trial that is run with the independent variable removed in order to insure that the change in data is indeed a product of manipulating that variable.)

Constants: Same testing pan, same time (therefore amount of sunlight), same soil, same worm throughout a trial (the constants are the variable that were the same for each trial, they are necessary in order to be sure that the experiment tests just what is meant to be tested)   

Experimental Hypothesis

If  the earthworms are exposed to sunlight, then they will crawl towards the shaded soil because the earthworms prefer shade to bright light.

Null Hypothesis 

If the earthworms are exposed to sunlight, then they will not crawl to the shade because earthworms prefer bright light to shade.  

How Do Earthworms React To Light?

Purpose

The purpose of this experiment is to investigate how earthworms react to differing amounts of light.
(The purpose is important because it lets others know exactly what you are investigating right in the beginning.)