Science Buddies: "Ask an Expert"

Last year, I did a project in 5th grade on bacteria. I tested the transfer and accumulation of bacteria on the key boards of students versus school nurses. The students had a higher bacterial growth, but the nurses had mold. I would like to continue this project but do not know how or what to look for. I assumed the nurses would have had more bacteria due to the work with sick students. I was wrong. But I wonder why the nurses had mold and the students did not. Was the mold significant, did it inhibit the bacterial growth or was it not important because mold grows everywhere. My control dishes had no growth, even after many many months so it was not related to contamination. The students dishes all had various levels of bacterial growth, while the nurses had slight bacterial growth but lots of mold. I am curious but do not know how to pose this as a workable question and what do I do. Help me if you can. I was unable to participate in the regional science fair due to being in 5th grade. My teacher encouraged me to continue project for 6th grade but I am not sure what that means or how to do so. Do I retest the same subjects but in a new way? DO I question the mold? HELP Matthew1.

Hi Matthew,

Sounds like an interesting project. Discovering that your first predictions were wrong is a common (and wonderful!) part of science, so it's great that you discovered "you were wrong." As I heard someone put it once, "science is not about proving that you ARE right, science is how you make sure that you BECOME right."

I just had a couple of thoughts about your experiment from last year. First, about the nurse's keyboards having fewer bacteria on them: can you propose a follow-up hypothesis to test, that could explain why the nurses' keyboards were less contaminated with bacteria? For example: if they are made from different material, are in use for fewer hours during the day, or if the nurses in your school wash their hands a lot more than the students do (which I certainly hope is true!), you could set up an experiment to find out whether that difference affects the accumulation of bacteria.

The other thought I had was prompted by your observation about mold. Since sometimes mold can be a problem in some rooms and not in others, I wondered whether the nurses' keyboards were in a different room from the students' keyboards. If the nurses' room has a mold problem but the classroom doesn't, that could explain the presence of mold spores on the nurses' keyboards. I mention this because it points out a common problem in experimental design: trying to ask whether one variable (for example, whether the person who uses the keyboard is a student or a nurse) affects another (microorganism growth), but accidentally introducing another systematic change (whether the keyboard is in the classroom or the nurses' office) at the same time. It's something to be careful about! The technical term for doing this is "pseudoreplication," and even professional scientists sometimes do it by accident. If you think that the room the plates were in might have made a difference, you might want to go back and find out whether there was any difference in the overall level of mold spores of the rooms.

-W

Hi Matthew,

I'm glad you were so successful with your original project, and are interested in expanding it.

To follow up with some of Walker's suggestions, you might be able to see if the bacteria vs. mold have to do with the room by adding new controls. You should still do your original (sterile) control plates to ensure that your results are not due to contamination. However, you might also consider leaving some open plates in each room for a day, and seeing if any mold or bacteria grow from just being in the air of the room. That allows you to test whether the microorganisms are in the air or specifically on the keyboards (from the nurses' or students' hands).

You can also ask the nurses and students about what they use to wash their hands. It is likely that the nurses use anti-bacterial soap or hand sanitizer on a regular basis, and this information could allow you to test a few things:
1) You could place some of the anti-bacterial agent (soap or hand sanitizer) on half of each plate before you swab the whole plate, and see whether the students' bacteria grows on the untreated side but not the treated side. (Wouldn't it be interesting if no bacteria grew on the treated side, but mold grew instead?)
2) You can do the same with the plates from the nurses' keyboards, and see whether the mold still grows in the presence of the antibiotic.
3) You could also swab the students' keyboards before and after applying some of the anti-bacterial agent to the keyboard itself, and then swab after you've treated it to see whether that reduces the amount of bacteria you grow from those keyboards.

As you have seen with the many responses so far, you have several ways in which you can expand your project. Please let us know what you decide to do so we can continue to help along the way!

Heather

I have my questions formulated for my this year's project. I though cannot decide how to narrow it down to one or two hypothesis. I know hypothesis is if and then statements... It just is not making sense to me this year. I know what I am going to do... I want to test for mold with an air study, test for mold by culturing, redo the swabs on the key boards, compare the bacterial growth on keyboards at elementary, junior high and high school...
I want to do a lot. I just do not know how to tie it into a couple hypothesis. Here are my questions I hope to answer:
• Why was there mold on the nurses Petri dishes last year and not much bacteria? Did the mold inhibit the bacteria?
• What kind of mold was it?
• Are the nurses over killing the normal bacteria in their environment making the mold spores more proliferate?
• Is the nurse’s office environment more prone to mold than the classroom? Why?
• Does the amount of bacteria found on a student’s keyboard decrease with grade level? Supporting as one’s age increases so does their knowledge and ability to wash one’s hands?
• Which door handle in the school has the most bacteria?
• What location in the school contains the most bacteria?
How do I get this in hypothesis format?

Hi Matthew,

matthew1 wrote:I have my questions formulated for my this year's project. I though cannot decide how to narrow it down to one or two hypothesis. I know hypothesis is if and then statements... It just is not making sense to me this year. I know what I am going to do... I want to test for mold with an air study, test for mold by culturing, redo the swabs on the key boards, compare the bacterial growth on keyboards at elementary, junior high and high school...

You have a lot of great questions! You may be thinking bigger than one or two hypotheses, so let's see if we can narrow things down for you.

matthew1 wrote:• Why was there mold on the nurses Petri dishes last year and not much bacteria? Did the mold inhibit the bacteria?
• What kind of mold was it?
• Are the nurses over killing the normal bacteria in their environment making the mold spores more proliferate?
• Is the nurse’s office environment more prone to mold than the classroom? Why?

I think all of these questions could fall under the same experimental study (and are a natural extension of the project you did last year. Your hypothesis could be something like:
"If people (nurses) use more antibiotics than others (students), you will see less bacteria but more mold."

To address each question individually, you might have sub-hypotheses:

matthew1 wrote:• Why was there mold on the nurses Petri dishes last year and not much bacteria? Did the mold inhibit the bacteria?

This is a great question to address with your experiment! Could it be that the nurses used a lot of antibacterial agents, so the bacteria disappeared; and now the mold has a chance to grow on the petri dishes? Or does mold inhibit bacteria (e.g., penicillin)? How would you test this?

matthew1 wrote:• What kind of mold was it?

An excellent follow-up question, which doesn't really require its own hypothesis. Do you know how to figure out what kind of mold you saw? (There should be references to help you identify mold species, or at least different genera.)

matthew1 wrote:• Are the nurses over killing the normal bacteria in their environment making the mold spores more proliferate?

This is one possible explanation for your first question. I would actually group it with that.

matthew1 wrote:• Is the nurse’s office environment more prone to mold than the classroom? Why?

This is another extension of your project from last year. The question is whether there is more mold in the nurse's office, or whether you were able to see the mold because there were fewer bacteria.

Your other questions are separate experiments:

matthew1 wrote:• Does the amount of bacteria found on a student’s keyboard decrease with grade level? Supporting as one’s age increases so does their knowledge and ability to wash one’s hands?
• Which door handle in the school has the most bacteria?
• What location in the school contains the most bacteria?

Each of these questions is its own experiment, though you could combine the last two.

If you only want one or two hypotheses, you need to decide whether you want to tackle the first group of questions (following up on the nurse's office results and the mold), or the second group. Let me know, and we'll work from there!