“The World of Germs”

We’re constantly telling our kids to wash our hands, and to be aware of germs. And we tell them that germs are “bugs” that can get inside our bodies where they grow and make us sick. Its hard for kids to wrap their minds around such abstract comments, and its hard for them to respect what they can’t even see. So just what do germs look like? We decided to answer that question once and for all.

Enter stage left: the petri dish.

First we mixed our germ food, a mixture of AGAR and CHICKEN BOULLION that we boiled in water.

My young’ns are too young to be mixing the chemicals and boiling water, so even with something as benign as agar and chicken boullion, mom did the heavy lifting during this stage. The kids did watch, tho, and we discussed the changes the powder made and the changes in the water color, consistency, and smell. Once we had our petri dishes mixed they had to cool. And they have to cool covered, or else random germs floating in the air might contaminate our microbe biosphere, so it takes a while. At least 24 hours before you can return with your test subjects and decide what to test.

None of us had been feeling well, so coughing was one of the first ideas.
As we were hacking and coughing the dog became concerned about our strange behavior and decided to investigate. And so we tested the dog. He wasn’t interested in touching the petri dish himself, so after letting him sniff it we patted the top of his head to the gelatin in the dish. After that, he decided he’d had enough of the nonsense and headed back to his spot on the couch. There were three of our five petri dishes already used up. We wanted to see how well soap worked, so on the bottom of one petri dish we drew a line down the center and wrote “dirty hands” on one side of the line, and “clean hands” on the other side of the line. We flipped the dish over, took off the lid, and on the side labeled “dirty hands” we touched and tapped with our dirty fingers. Then we dashed to wash hands and returned, refreshed after our race to the sink, to tap and poke the side of the dish labeled “clean hands.” The clean/dirty hand experiment is great, too, because

young scientists are rabid to touch things. They can’t touch random petri dishes, tho, because it will contaminate the sample. This way they not only get to see whats on their hands, but they get to satisfy their tactile sensory needs as well.

And finally, for our remaining dish, the kids chose an object from the house, whatever they wanted, to test for germs. My daughter returned with a book, an excellent choice. “Do you think there will be any germs on this book?” I asked her. “Ummm… no,” was the reply.

Three days later: Germ check. We’re starting to get somewhere! Although we were fairly unimpressed with the amount of growth in three days. I’m not sure what we were expecting, but I thought we’d have something more impressive at this point. Little did I know, Impressive was on its way… Anyhoo, the clean hands/dirty hands dish showed a drastic difference in the amount of germ colonies. The kids were impressed with this. “Le Dog” was also proving to be good and dirty, nothing unexpected there. The red of the growth in his dish was alarming. It brought to my mind thoughts of poisonous plants and tree frogs… In nature the really dangerous stuff is frequently the most beautiful, and I wondered what we had growing in our dish…

The petri dish with the book swab was boring, as were the dishes we’d coughed in.

Now that we had some germ colonies rolling we pulled out the antibiotic ointment.

We swabbed some on each dish to see if it retarded or killed the germ growth.
We recapped the dishes and returned them to their spot in the pantry… Two days later I was walking by and happened to glance up and startled in surprise. Our germs had been busy!

Apparently the antibiotic ointment wasn’t particularly effective in retarding the growth of our germ colonies.

This photograph is of the clean hands/dirty hands. I’m showing a pic of the underside of the petri dish as well as its easier to see the difference in amount of germ growth on either side of the line.

Following are pictured the dish of “le dog,” its the one with the most aggressive growth, the book with moderate growth, and a dish of my daughter’s cough. We had very little from her cough, something else that surprised us.



Now we know what germs look like. They can grow to look like fuzz, hair, pulp, liquid, and they can be a myriad of colors. We learned that germs are everywhere, from books to beasts, and we have concrete evidence that our coughs contain germs as well. Most importantly we learned that washing hands with soap can help keep us healthy by removing germs from our hands.

In retrospect, we should have had a control dish of just antibotic ointment, a dish touched by dirty hands only, a dish where we’d touched the agar w/ dirty hands and then immediately applied antibiotic ointment, and then a dish where we’d applied the antibiotic ointment after the germs had built up colonies. But I’m not that organized, however its a great idea for future experimenting! This idea could be taken even further to compare the effectiveness of different types of antibiotic ointments… Hmmm…

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Salt Crystal Experiment


What to do on a cold, rainy day? Science experiments!

My little lady LOVES crystals, and anything to do with magic and fairies. So when I asked her if she’d like to grow some crystals she became very excited and went to get her brother for support!

Materials:

Two small cups
String (we used embroidery floss – about six inches)
Salt
Water
Screws (or nails – something to weigh down the ends of the string in the water)
Something to mix with
TOWELS, for life’s unexpected happenings.
One or two willing scientists!

This experiment is great for the younger crowd because accurate measurements aren’t necessary.

Before you get started it might be fun to taste the water and the salt and talk about how the water tastes before the salt is mixed in (well it doesn’t taste salty!), what it looks like (i.e. clear, you can see through it), and maybe do a practice stir in the plain water and talk about how easy it is to move the spoon or whisk through the water at this point. You can also take a close look at the string – is it soft or hard? Does it taste like anything? Etc.

It is time to begin the experiment. First pour the salt into the cups:

You don’t need TOO much salt – I tried to reign in my eager scientists when the salt reached about a half inch in depth.

Next, pour the water:

Again, try to stop the water from filling the cup. About half full is good.

Mix the salt and water to make a SOLUTION.

Query: What is a SOLUTION? A solution is
a.
the process by which a gas, liquid, or solid is dispersed homogeneously in a gas, liquid, or solid without chemical change.
b.
such a substance, as dissolved sugar or salt in solution.
c.
a homogeneous, molecular mixture of two or more substances.

Its easier for kids to understand that the salt disappears in the water but doesn’t go away. This is a good time to revisit the earlier observations of the water and salt before they were combined and discuss what’s changed. (Ex: the water is no longer clear, but cloudy, it tastes salty, its possibly more difficult to stir, it might smell bad, etc.)

NEXT: tie each end of the string (oh, and you only need about six inches of string – I had way too much) around your chosen weight (in my case it was screws) and drop one end into each cup so they’re connected.

Now that you have two cups of salt water connected by a string bridge it’s interesting to ponder what might happen. Also known as forming the hypothesis.

Young scientists might have trouble forming a hypothesis at the beginning of an experiment, or understanding what hypothesis means. Sometimes the picture becomes more clear once everything is set up and the concept of hypothesis is easier to explain after its happened.
Some possibilities to guide your scientists to consider are, do they think the string will absorb the water? What about the salt? What does evaporation mean? Will salt evaporate or just the water? And so on. Also take a minute to sit and watch the string. Is anything happening? No? Hmmm… Maybe tomorrow, then. Find an out of the way spot to put your experiment and check back 12-24hrs later.

And here’s what you can expect to happen after about 24 hours – salt crystals are beginning to form along the string where it laps over the edge of the cup. Given enough time and water and salt, there might begin to form in the center of the string salt stalagmites and stalactites. We did not pursue those formations in this experiment. Instead we were satisfied to see the salt was carried up the string by the water and then left behind when the water evaporated. Other things to notice at this point, the string is now stiff and crunchy, not soft and bendy as in the beginning. If kids are curious as to what the crystals are, suggest they give them a little lick. It will become obvious quickly that it is indeed salt!