Hypothesis, Variables, Materials, and Procedures
HYPOTHESIS:
If the moisturizers for sensitive skin work then the moisturizers with jello should get heavier because it is absorbing the moisturizers in place of water just like if you were to use a moisturizer for dry skin.
INDEPENDENT VARIABLE:
The independent variable in my experiment was the brand of moisturizer that I used.
DEPENDENT VARIABLE:
The dependent variable in my experiment was the weight of each petri dish that contained the moisturizer (independent variable) and jello.
MATERIALS:
If the moisturizers for sensitive skin work then the moisturizers with jello should get heavier because it is absorbing the moisturizers in place of water just like if you were to use a moisturizer for dry skin.
INDEPENDENT VARIABLE:
The independent variable in my experiment was the brand of moisturizer that I used.
DEPENDENT VARIABLE:
The dependent variable in my experiment was the weight of each petri dish that contained the moisturizer (independent variable) and jello.
MATERIALS:
- Permanent marker
- Different skin moisturizers to test (at least 5). You will need 3 fluid oz. of each one. Look for products marketed specifically for "dry skin." See Figure 2 in the Introduction in the Background tab for examples of what to look for. Pick at least three of the following five types of skin moisturizers to test (examples of each type are given):
- A moisturizer that lists glycerin as the second ingredient, after water. Make sure it does not also contain triethanolamine.
- A moisturizer that lists glycerin as its fourth or lower ingredient (and does not contain mineral oil or petrolatum [petroleum jelly] among the first three ingredients, or triethanolamine anywhere in the list). This may be a cream that is mostly oil and/or butter-based.
- A moisturizer that lists mineral oil as the first or second ingredient. This may be an ointment. If mineral oil is listed as the first inactive ingredient, it can be used if only one active ingredient is listed and it is less than 50%. Make sure it does not also contain triethanolamine.
- A 100% petroleum jelly moisturizer.
- A moisturizer that contains triethanolamine somewhere in the ingredient list. This may be a lotion that lists glycerin as the second ingredient, after water.
- Note: If you use the example products given, be sure to confirm the ingredients list on the product, as manufacturers might change their formulas.
- Petri dishes, 100 mm diameter x 15 mm deep (18, or three dishes for each skin moisturizer you test plus three more for controls).
- JELL-O® gelatin dessert (two 3-oz. packages are needed for 18 petri dishes)
- Stove
- Measuring cup
- Cooking pot
- Clock or timer
- Stirrer
- Cup with a pouring spout
- Graduated cylinder (50 mL volume)
- Refrigerator
- Paper towels or rags
- Scale, which must be able to accurately measure 0.1 g increments. A digital scale that is this accurate (the Fast Weigh MS-500-BLK digital pocket scale) Measuring tablespoon
- Optional: Plastic wrap
- Plastic knife or butter knife
- Ruler, metric
- Optional: Camera
- Toothpick
- Calculator
- Lab notebook
In this experiment you will need to use the stove, so make sure you have adult supervision or just be really careful. Below are some pictures of the materials you will need.
You can follow these steps or come up with your own hypothesis based on your experiment.
1. Label each of your moisturizers (1, 2, 3, 4, and 5) with a permanent marker.
2. Assign and label three of the petri dishes to the moisturizers.
3. Label the three petri dishes in each moisturizer group with the number and then write a, b, or c on the petri dish afterward. Look at the picture on the far left and middle to know how to label each of the moisturizers. Don't forget to leave 3 petri dishes out for the control group. This will make it easier to compare your data and know which moisturizer to use.
4. After you have assigned the numbers to the moisturizers and petri dishes, label and write them down in your notebook.
5. Triple the experiment because it helps you show that you did the experiment accurately and it is reproducible.
6. In your lab notebook, also write the moisturizer's name and the number 1-6 (6 is the control group).
Look at the picture on the far right to see how you should label everything in your notebook.
2. Assign and label three of the petri dishes to the moisturizers.
3. Label the three petri dishes in each moisturizer group with the number and then write a, b, or c on the petri dish afterward. Look at the picture on the far left and middle to know how to label each of the moisturizers. Don't forget to leave 3 petri dishes out for the control group. This will make it easier to compare your data and know which moisturizer to use.
4. After you have assigned the numbers to the moisturizers and petri dishes, label and write them down in your notebook.
5. Triple the experiment because it helps you show that you did the experiment accurately and it is reproducible.
6. In your lab notebook, also write the moisturizer's name and the number 1-6 (6 is the control group).
Look at the picture on the far right to see how you should label everything in your notebook.
See how to make the gelatin for the petri dishes below.
7. First pick the color of jello. You want to get at least 2 boxes of jello because you want to have at least 50 milliliters of gelatin dessert. If you want to fill 18 petri dishes then you have to prepare at least 900 mL which is equivalent to 2 packets of the gelatin. This will allow extra in case you drop one of the petri dishes and have to start over.
8. On the stove, boil 1 cup of water per package. Add the gelatin dessert to the water. Continue to stir the mixture (like the picture on the far right) for at least 2 minutes or whenever it looks like most of the gelatin dessert has melted into the water or it starts to boil again.
9. Take the gelatin off the burner and add 1 cup of cold water per package to the gelatin and continue to stir as you add the water (look at the picture on the far left to see me holding the spoon at the same time as I am pouring in the water).
7. First pick the color of jello. You want to get at least 2 boxes of jello because you want to have at least 50 milliliters of gelatin dessert. If you want to fill 18 petri dishes then you have to prepare at least 900 mL which is equivalent to 2 packets of the gelatin. This will allow extra in case you drop one of the petri dishes and have to start over.
8. On the stove, boil 1 cup of water per package. Add the gelatin dessert to the water. Continue to stir the mixture (like the picture on the far right) for at least 2 minutes or whenever it looks like most of the gelatin dessert has melted into the water or it starts to boil again.
9. Take the gelatin off the burner and add 1 cup of cold water per package to the gelatin and continue to stir as you add the water (look at the picture on the far left to see me holding the spoon at the same time as I am pouring in the water).
After you have finished pouring in all of the water, make sure you have a clear space that is also flat so you won't spill anything.
10. Pour 50 mL of the gelatin dessert into each petri dish (look at the picture on the far left and in the middle to see how to spoon the gelatin out and measure it). Use a ladle to help transfer the gelatin from the pot to the measuring cup (count how many scoops it takes so instead of having to pour little by little into the measuring cup you know, for example, that 2 big scoops and one half scoop equaled 50 mL).
11. Slowly start to pour the gelatin into the petri dishes (look at the picture on the far right to see how to pour the gelatin into the petri dishes). Try to work as quickly as you can without spilling anything during the process.
10. Pour 50 mL of the gelatin dessert into each petri dish (look at the picture on the far left and in the middle to see how to spoon the gelatin out and measure it). Use a ladle to help transfer the gelatin from the pot to the measuring cup (count how many scoops it takes so instead of having to pour little by little into the measuring cup you know, for example, that 2 big scoops and one half scoop equaled 50 mL).
11. Slowly start to pour the gelatin into the petri dishes (look at the picture on the far right to see how to pour the gelatin into the petri dishes). Try to work as quickly as you can without spilling anything during the process.
The gelatin dessert should fill a little more than half way of the petri dish (look at the picture on the left to see how the petri dish is supposed to look).
12. When you have finished filling all of the petri dishes, put the lids back on the dishes, if you haven't already done so, and put them in the refrigerator where they will not be disturbed for at least 4 hours. Try to move as quickly as possible but make sure you don't spill anything. You can try and stack each of the dishes on top of each other and put them on a platter or in a plastic container to prevent them from falling out while you put them in the refrigerator.
12. When you have finished filling all of the petri dishes, put the lids back on the dishes, if you haven't already done so, and put them in the refrigerator where they will not be disturbed for at least 4 hours. Try to move as quickly as possible but make sure you don't spill anything. You can try and stack each of the dishes on top of each other and put them on a platter or in a plastic container to prevent them from falling out while you put them in the refrigerator.
When you take the gelatin out of the refrigerator the jello should be hard like jello.
13. Add 2 tablespoons or 30 mL of one the moisturizers to each of the three petri dishes. (NOTE: You can try putting a plastic wrap inside of the measuring cup. It was hard for me to scrape out the moisturizers, so I ended up not using the plastic wrap and washed the measuring cup after I was finished. (look at the pictures on the far left and in the middle). Make sure the moisturizer covers the top of the petri dish and is smoothed out, using a plastic or butter knife (look at the picture on the far right and see how I used to butter knife to level out the moisturizer in the petri dish). Don't forget to leave three dishes with no moisturizer for the control group.
13. Add 2 tablespoons or 30 mL of one the moisturizers to each of the three petri dishes. (NOTE: You can try putting a plastic wrap inside of the measuring cup. It was hard for me to scrape out the moisturizers, so I ended up not using the plastic wrap and washed the measuring cup after I was finished. (look at the pictures on the far left and in the middle). Make sure the moisturizer covers the top of the petri dish and is smoothed out, using a plastic or butter knife (look at the picture on the far right and see how I used to butter knife to level out the moisturizer in the petri dish). Don't forget to leave three dishes with no moisturizer for the control group.
14. In your lab notebook record any observations that you have about how the petri dishes and how they look and feel.
15. Then weigh each of the petri dishes and record how much they weigh before and after weighing the jello. If you want you can take lots of pictures to show how the experiment is going.
16. Also write down what time you measure the petri dishes so you know when you have to measure the dishes around that time.
17. Continue to weigh the dishes for 2 weeks around the same time each day.
18. Along the way make sure to write down any other observations you have. You can even try leaving it out of the refrigerator or inside, you can even try both!
15. Then weigh each of the petri dishes and record how much they weigh before and after weighing the jello. If you want you can take lots of pictures to show how the experiment is going.
16. Also write down what time you measure the petri dishes so you know when you have to measure the dishes around that time.
17. Continue to weigh the dishes for 2 weeks around the same time each day.
18. Along the way make sure to write down any other observations you have. You can even try leaving it out of the refrigerator or inside, you can even try both!