A couple of you asked, in comments if I would share the kids' science projects. So, this is P2's.
Question: Does cleaning every day, as compared to cleaning every other day, make a difference in the amount of organic organisms on kitchen surfaces?
Hypothesis: I think cleaning every other day is better because as soon as you touch something after you clean it, it's contaminated.
(Pmomma's note: I'm biting my lip to not have him redefine his hypothesis. I think the term "better" is suggestive and needs to be reworded. But, it's his project...*bites lip*).
Methodology/Experiment: These are the steps I need to take for my experiment.
1. Get empty, sterile petri dishes and agar medium from the internet.
2. Wash hands thouroughly and put on gloves so I don't taint the dishes or the agar.
3. With gloved hands, heat the agar and pout it into dishes to a depth of 1/4 inch. Repeat fifteen times. Label three dishes as "control".
4. Quickly place lids on dishes and place on sterilized (with running alcohol) cookie sheet. Place on sterilized shelf in fridge to cool and harden.
5. Wait 24 hours.
6. Build an incubator. I used a plastic tub with a good lid. I ran it through our dishwasher to sterilize it and used gloves to transport it to my room. I picked a sunny shelf by the window and put a bathtowel on the shelf. I then put a heating pad down. Then, I put another clean towel. I checked the inside temperature at 1 hour and 4 hours and 8 hours to make sure it was a constant 95 degrees F.
7. I took five samples from our kitchen where we cleaned on a schedule of every two days. We used the same cleaning product as my grandma (we split bottles of cleaning solution for this experiment to eliminate a variable). My five places were; tile by the sink (one inch from the edge), bottom of sink, refridgerator handle, one inch from the leading edge of the trashcan on the floor, and in the exact center of the stove tops. I used a hard plastic template that had been sterilized between swabs with alcohol. I used the template to eliminate the variable of tested space.
8. I did step seven at my grandma's house.
9. The samples went into the incubator for seventy-two hours. We have one control that was taped closed as soon as it firmed up in the fridge. One sample was opened in our kitchen while I swabbed the surfaces. The other was open at my grandmas. This should tell us if there was an air based variable since we didn't swab these controls.
10. Every twelve hours, we rotated the petri dishes in the incubator to insure the same exposure to light and heat. We also checked the thermometer every four hours.
11. After 72 hours, we removed the samples and photographed the dishes.
12. After photographing, we used a Sharpee pen to count the samples from the back side of the slide.
(Pmomma note: he needs to change the word "slide" but...again, his project. *bites tongue*)
13. We counted anything under a 1/8inch diameter as "1". Between 1/8 and 1/2 inch got a "2". Between 1/2 and 1" got a 3. Anything over an inch was given a value dependent on the diameter. For every thing above 1", we used the already stated values to add on points as necessary.
14. We also added up our points and figured out, using math, how much of the surface (percentage wise) was taken up by organic growth. This was really hard but it ended up being a good check on the point system.
That's as far as he's got with the writing.
The pics are here.
If you want captions, go here: