scientific method, uh... Options

[LULLABYxx]

I'm having a problem using the scientific method for this experiment.

Can anyone tell me what the independent variable for this experiment is...if I can just get what the IV is...I can figure out the rest pretty easy...oh..and what could the control be? I think that's it..I'm really not trying to get anyone to do my homework. I'm just having problems with those two.

This experiment was conducted to see which common fruit has the most Vitamin C. You’ll be surprised since most people have a lot of misconceptions about this question.
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MY HYPOTHESIS: Nutritional analysis of the vitamin content of common fruits conclude that some fruits have much higher Vitamin C content than others. Most people seem to think that oranges have the highest Vitamin C. However I think that kiwis and papayas have the most Vitamin C based on research. Kiwis are supposed to contain the most Vitamin C while papayas are also supposed to contain the most of this important nutrient. Did you know that kiwis are twice as rich in Vitamin C than oranges? Or at least, that is what scientists and nutritionists have concluded. I will conduct an experiment to see if these facts are true and which common fruit really does have the most Vitamin C.
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The Vitamin C detective: In order to figure out the relative content of Vitamin C in fruits, I discovered an indicator solution that can easily be made from common household ingredients. The indicator solution binds to the Vitamin C. The more Vitamin C there is in a substance, the clearer the color. And presto! You now have an easy way to compare the Vitamin C levels of common fruits.
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MATERIALS:
Cornstarch
2% iodine solution
Tap water
Measuring spoons
An eyedropper
Test tubes
A papaya, a kiwi, an orange, a grapefruit, a lemon and a pineapple
A bottle of grapefruit, lemon and orange juice from concentrate
A blender to obtain the juice from the fruits
A stove (make sure to ask an adult for help)
Pots

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METHOD:
Mix 1 tablespoon of cornstarch into enough water to make a paste.
To this paste, add at exactly 250 milliliters of water and boil for five minutes. Allow to cool.
Add 10 drops of the starch solution to 75 milliliters of water by using your eyedropper.
Add enough iodine to produce a dark purple-blue color. Now your indicator solution is ready.
Put 5 milliliters of indicator solution (roughly 1 teaspoon) in a 15-milliliter test tube (one for each sample).
To the test tube, use a clean eyedropper to add 10 drops of juice from your fresh fruits. For solids, pulp them in a blender and strain the juice well. Wash and clean the eyedropper for each sample. Shake well.
Place all of your test tubes against a white background.
Line up the tubes from lightest to darkest purple. The lighter the solution, the higher the level of Vitamin C content. That’s because Vitamin causes the purple indicator solution to lose its color.

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OBSERVATIONS:
I observed that when I combined the iodine with the cornstarch solution, the iodine swirled around the cornstarch solution. As well, there were tiny bubbly ***** that had been created by the iodine.
Over the course of a few hours, I saw that the substances with the fruit juices became extremely clear and pale blue.
I remarked that when I put the juice from the fruits in a test tube, along with the indicator substance, the reaction between the chemicals was immediate.
After one day, I observed that the cornstarch solution, on it’s own, became very thick, heavy and pasty as a result of making it the previous day. Therefore, I would suggest if anyone would like to replicate this experiment not make your cornstarch solution the day before you do the experiment; make it fresh while you are doing it.
Finally, I looked deeply into the test tube with the juice from the grapefruit and there were small splotches in the indicator substance. Why? Because I did not shake the indicator substance thoroughly with the juice from the grapefruit.


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THE RESULTS:
Juice from papayas has the most vitamin C! In the test tube, the color of the substance was orange, a bit like the inside of the papaya, and clear.
In second place, there is the kiwi juice. The color of the substance was green, exactly the same as the middle of a kiwi, and clear.
After the kiwi, there’s the orange juice. Most people believe that the orange has the most Vitamin C compared to other fruits. I’ve demonstrated through this experiment that oranges do not deserve the credit for being the fruit with the highest vitamin C content. In the test tube, the color of the substance was blue and clear.
In fourth place, there’s the grapefruit. With this fruit, the color in the test tube was blue, clear and dark, all at the same time. It’s a little difficult to visualize.
Right behind the grapefruit, there is the lemon. In the test tube, the color of the substance was simple, plain old blue.
Last, but certainly not least, we have the pineapple! With this fruit, the color in the test tube was a dark purple-blue.


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CONCLUSION:
In conclusion, my hypothesis was half correct, as I had anticipated that both kiwi and papaya would be similarly high in Vitamin C content. However, the fruit with the most Vitamin C was the papaya! So, if you want to stay healthy and strong, eat fresh papayas, as they are full of Vitamin C!
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FRUITS RANKING
Papaya
1st
Kiwi 2nd
Orange 3rd
Grapefruit 4th
Lemon 5th
Pineapple 6th