Awaken Yeast

Swipe your hand through the air. Now look at it. Chances are you have brushed against thousands of yeast particles in that brief sweep because yeast, a living organism, exists on most surfaces and in the air all around us. It covers your skin. It is usually dormant…you can think of it as a sort of deep sleep or hibernation. While dormant, yeast doesn’t actively grow. It’s waiting and it can wait a long time. Scientists have found yeast in Egyptian ovens dating over 3000 years old. They woke up the yeast and used it to produce loaves of bread.

How do you wake up yeast? Warm water and sugars is the quick answer.

Why would you care about yeast? Here, we’re talking about culinary yeast. Yeast makes bread fluffy, and some drinks fizzy. That’s because, when yeast is growing, it exhales air and makes bubbles.

In fact, all living things respire to create and release energy. Alternatively, if an organism breathes, it is alive.

Your Breathing:

Activity 1: Take a big breath and then exhale. Do this a number of times, thinking about why we must breathe. This is one of the big differences between living and nonliving objects. If it breathes, it is alive. Rocks, for instance, do not breathe. Breathing involves two basic steps: taking air into our bodies and letting the air pass out.

Activity 2: Put a straw into a glass of water and blow into it. Watch bubbles form. Try blowing soft and slow; then fast and hard. How do the bubbles change? When you blow into the straw, you are exhaling. This simple activity makes our breathing more visible.

Observing yeast respiration (yeast breath!)

Activity 3: Sprinkle a teaspoon of baking yeast over a bowl of lukewarm water. Wait thirty seconds to see what happens. How did the yeast change?

Activity 4: Add 1 tablespoon brown sugar to the bowl and stir gently to dissolve the brown sugar. Now watch what happens to the yeast.

Activity 5: Start with a new bowl, this time with ice water. Sprinkle yeast over the top and observe.

Activity 6: Starting with another bowl, sprinkle yeast over boiling hot water and observe.

What happened:

Warm water activates dormant yeast, which will start to grow. Bubbles and even movement might be observed in the yeast. However, like other living organisms, yeast needs energy to grow and water doesn’t provide energy. Brown sugar is an excellent source of energy. The yeast will start to foam and bubble. How is this similar to breathing activity #2? Observe closely and you can see yeast moving throughout the liquid, and sometimes you can even feel the air being exhaled by the yeast (if you get close enough). Yeast breathes oxygen and exhales carbon dioxide just as we do.

Yeast sprinkled over the ice water will take a long time to activate, even with brown sugar added. Yeast sprinkled over boiling hot water will die. Yeast needs just the right temperature (warm to your hand) to grow. That’s why some bakers have trouble making yeast bread: they don’t get the temperature just right.

Why do bakers use yeast?

The bubbles make bread dough rise. Baked bread is fluffier. Yeast is also used to make some fizzy drinks.

How is commercial yeast made?

Yeast buds are grown in factories, just as you did in activities 3 and 4, except they are grown in large vats and molasses is used for energy. Brown sugar contains molasses, too. Then the growing yeast is scraped off the top of the vats and gently dried. Without water, the yeast stops growing and goes dormant. It is put into pouches or jars for storage. Refrigerating the yeast at home helps keep it viable for much longer.

There are many types of yeast

Some yeast is used for baking, others for nutrition, for making beer or champagne. Another type of yeast that grows on human bodies can cause problems, but mainly when the yeast comes in contact with warm moist regions that are covered by clothing.

Fun for teachers:

Use a clear, narrow glass to grow the yeast. Spread paper towels below the glass. Fill the cup 3/4 full of warm water; then add 1/2 tsp yeast and 1 tsp brown sugar and stir. The point here is to make the yeast grow and foam over the top of the glass, but don’t tell your students in advance. Students will watch the yeast slowly grow…then faster and faster until a huge foam head forms and spills over the side. You should experiment with the proportions and glass beforehand so you get the right effect. Glorious, especially if the teacher acts as surprised as the students.

Catch Your Shadow

On the recent winter solstice (Dec 20, 2020) I asked a friend to help me capture my noon shadow.

“How would I do that?” she asked.

I unrolled a length of black felt and gave her a piece of tailor’s chalk. “Follow me outside. But be quick,” I added. “Solar noon is about to happen.”

Shadows are so much fun to have in your drawer. I used to have an entire collection of them, which I would take to elementary schools. Those have been lost during my several home moves, so I decided to start a new collection. Now I asked my friend, “How long do you think my shadow will be?” “Well, it will be short since it’s noon. Maybe you won’t even have one.” She eyed my yardage. Then we went outside. I looked at my watch: 11:59 a.m., exactly solar noon.

I unrolled the fabric and stood so that my shadow fell on it. My friend began tracing it with the chalk. She had to move quickly because the shadow began shifting away from her tracing. Luckily, it was noon, when the shadow moves slowest. If we’d been working at sunset, she wouldn’t have been able to keep up. When I had caught sunset shadows for my previous collection, two of my children would trace frantically to beat the sun as it advanced and my shadow slid out from under me. “Oh, Mom,” they would complain. “Why do we have to do this?” I had interrupted their computer game.

This isn’t my real shadow; it’s a piece of felt fabric

On winter solstice, the sun carves its lowest arc across the sky. A low angle meant shadows would be longer than on any other day of the year. I’d purchased 3 yards of felt at the fabric store the previous night and even that wouldn’t be long enough to capture my shadow. I had to cut off a piece of fabric from the excess folded part and use it to extend the fabric. Even I was surprised at the length of my shadow: it was approximately 10 feet!

I’m lying atop my felt shadow

Now my friend’s husband Mike joined us. “What is the angle of the sun now?” he wondered. “Can you measure it from your shadow?” Yes, you could. My vertical body and the length of the shadow created a right triangle. The angle of the solar height could be computed from this. The angle cast by a stick and its shadow on a summer solstice several thousand years ago is the means used by Eratosthenes to calculate earth’s circumference. That will eventually be another lesson plan!

Mike took out his cellphone and used an app to find true north and we marked its line directly on the shadow for reference. I was surprised, but shouldn’t have been, to find that my shadow was pointing due north, directly toward the north pole. At noon in the northern hemisphere, shadows will always point true north, which is why taking noon sightings were so important for mariners in the days before geo-positioning satellites. (You can have fun confounding people by asking them if they can make their shadow reverse direction, pointing in the opposite direction. Often, they will try repositioning their body before they realize it’s impossible and then they will ask why it’s impossible. We all know that shadows move as the day goes on. Why can’t you get it to point south? North of the tropic of Cancer the sun is always to our south, meaning that shadows will always point northward)

Think of all the ways shadows can be used! Really, the list is endless. Sundials, moondials, Marsdials. Shadows give you an idea of the quality of light in pictures and are used to create realism in cartoons and paintings. As above, shadows can give direction and help determine latitude. Shadows have helped astronomers identify craters on the moon. Over 2000 years ago, Eratosthenes used a noon shadow at summer solstice to determine the circumference of the earth.

What is “solar noon?” That’s when the sun is at its highest point in the sky. It would be easy to say, “when the sun is directly overhead” but that’s not true on most parts of the earth. Where I live at latitude 38 degrees north, the sun will never be directly overhead. And, solar noon is rarely at 12:00 on our watches. Time zones have put our watches out of sync with the sun. To find the “watch time” that corresponds to solar noon, you can look at the NOAA website or merely google solar noon on the date in which you are interested. It was a coincidence of factors that made solar noon nearly the same as clock noon on this latest solstice 11:59 p.m.

What is “true north”? That is the line that runs directly to the north pole, or to the north star at night. It is not the same as magnetic north. because the magnetic north pole is to the east of the true north pole. True north is the one used for navigation. The difference between true north and magnetic north varies from place to place and is computed as an angle. At latitude 38 north, the difference is a whopping 15 degrees. Before cellphone apps, you could use a compass to find magnetic north, look up the angular difference on a table; then use a protractor to redraw the line. Of course, you can still do this. Pay attention to the direction of the angle! Since magnetic north is to the east, the true north line will be rotated to your left.

The best time to take standardized shadows is on the solstices and equinoxes, but any time is fun. Best to take each shadow at solar noon for accurate comparison among them. So much fun! Use felt because it doesn’t ravel when cut. I like to decorate my shadows with embroidery.

Teachers in Ghazni, Afghanistan learn about shadows in a workshop led by Camilla Barry

Copper Doorknobs and Your Health

I was so excited by something I learned yesterday that I stayed up long into the night on my motel internet reading about it.

Here’s the back story. I’m traveling cross country looking for a new home and exploring along the way. In Arizona I stopped at Jerome, a once-ghost-town that is now an artist colony. Jerome was a copper mining town perched high on a mountain slope. Because the town began slipping down the slope, and for other reasons, a company town Clarkdale was built in the Verde valley below. Had to visit that! A sweet little town full of Craftsman homes built around a square…and a great copper museum inside the old high school!

The display that caught my attention was about copper’s ability to destroy microbes. Who’d a thunk? Maybe everyone else knew this. The museum curator told me that many metals disrupt microbes but that copper is possibly the best. A scholarly article I read explained that copper releases electrically charged particles (ions) when a microbe lands on its surface. A microbe includes viruses and bacteria. The ions punch holes in the surface of the virus and destroy the rna and dna inside, so it can’t reproduce. (See my earlier article about hand washing and the corona virus).

This is one reason some hospitals use copper doorknobs. The old high school itself had copper door knobs. Copper reduces infections. Why don’t more health centers use copper? It is expensive.

This article doesn’t yet include photos or citations because I’m using my iPad and I haven’t figured out how to paste them. I also can’t do experiments while traveling but here is an idea for an activity:

Moisten some bread and allow it to sit in a bowl for a few days until it is moldy. Then place some pure copper wire across part of it and see what happens. Is mold considered a microbe? I’m not sure. A piece of copper pipe or sheet of copper would be better. Why not use a penny?

Two similar recipes; vastly different health effects

My Dad, Clavis Hinshaw, also known as CJ

My dad, known as CJ, grew up on a poor farm in central Indiana. His ancestors had lived in North Carolina and he still thought of himself as a southerner. He spoke often of the food he ate as a child, no doubt carried along with his ancestors when they migrated from North Carolina to Indiana in what is known as “the great migration.” A staple in his childhood diet was cornmeal mush, or simply mush. Here is a recipe for it, adapted from the website All Recipes:

Cornmeal Mush:

1 1/2 cups Cornmeal, 2 1/2 cups water, 1 teaspoon salt. Put all three ingredients in a heavy pan and bring to a boil, stirring constantly to prevent burning. When the water has been absorbed and the meal all incorporated, remove from heat. Serve as a sweet cereal with cream and maple syrup or as a savory dish.

Cornmeal Mush

Simple! Now compare that recipe to a recipe called sofki, traditionally developed by native Muscogee Indians in the southern United States and eaten perhaps for centuries before encountering Europeans. This recipe is adapted from the website


Place about three pounds flint corn in a bucket of water and let stand until kernels are soft. Drain the kernels and pound in a mortar while still wet. Remove any large or hard chunks. Put the ground grains into a kettle with three times the amount of water. (1 part grains to 3 parts water). Bring to a boil, watching carefully to avoid burning and stirring as necessary. When the mixture comes to a hard boil, add kvpe-cvfke, a drop at a time until the corn turns a slight yellow. Continue to boil, stirring often, until the liquid thickens and the corn is soft. Serve as a sweet cereal or as a savory dish.

Creek Indian Woman Sifting Sofki

Both recipes use ground corn and boiled water to create a mushy dish. Can you spot the difference in ingredients? One recipe led to a widespread disease in the American south, and the other prevented it. The difference is kvpe-cvfke, the Muscogee word for hardwood ash water. The disease it prevented was pellagra.

Pellagra victim

Hardwood ash water is created by dripping and straining well water through a bucket of hardwood ashes. That water then has an alkali in it, sometimes known as lye. Adding lye water to the corn as it cooked unlocked a vital nutrient: niacin. You encounter corn treated with lye if you buy hominy or hominy grits in the modern supermarket. Regular corn meal has not been treated this way. That’s not a problem if you eat a balanced diet, but poor white southerners often relied on corn as a staple in their diets and may not have supplemented it with enough fresh vegetables or meat. Lack of niacin in their diets resulted in pellagra, a disease that could cause the “four D’s”: diarrhea, dermatitis, dementia, and death.

It is interesting to note that Spanish explorers encountered corn being prepared this way by Native Americans. Spaniards introduced corn and corn meal to Europeans and European Americans but left out the important alkali process, also known as nixtamalization. Indiana, where my dad grew up, was rich in the tradition of eating cornmeal products. Corn was easy to grow in the farmlands created by cutting down vast forests. Grist mills were common on the creeks and rivers, and were a source of income for mill owners. It was easy and relatively inexpensive to take corn left over from feeding the hogs, to the mill for human consumption.

The discovery of the benefits of niacin and the prevention of pellagra makes for interesting reading. During the early decades of the twentieth century, the source of pellagra was at first thought to be germs. But the germ couldn’t be found and infection didn’t pass from one person to another. Still, the germ theory held on. A researcher Joseph Goldberger discovered that a balanced diet prevented and cured pellagra, but searched in vain for the reason. His suspicions of diet-caused pellagra were scoffed at. In one set of experiments, he fed dogs a diet rich in cornmeal such as the diet pellagra sufferers ate. The dogs weren’t interested in the food, so he added brewers yeast to stimulate their appetite. Dogs who ate cornmeal supplemented with brewers yeast did not get pellagra; other dogs did. It turns out that brewers yeast is rich in niacin. The missing element had been found.

How did scientists learn that adding lye to corn releases niacin? That calls for more research on my part.

You can try both recipes above to explore taste differences, or you can buy hominy grits from the supermarket and compare it to regular cornmeal grits (often known as polenta). For a more authentic Hoosier recipe, buy coarse ground cornmeal from an operating gristmill. Polenta is an excellent and tasty dish and I certainly prefer the name to cornmeal mush. Just don’t eat it exclusively.

Do It Yourself

I drove to a local Mexican grocery store over Christmas and perused their goods. Many Mexican chefs cook up tamales for the holiday and they do it from scratch. This calls for corn which has undergone the nixtmalization process. I bought a bag of corn and a container of “Cal” displayed alongside. Cal is calcium hydroxide, used in place of wood ashes or lye, to treat the corn. Online information says that Cal is less caustic than lye and gives the corn a better flavor. In a sign of the times, none of the store clerks knew how to use these ingredients. The butcher, a man who spoke only Spanish, was able to confirm that I had the right ingredients, via an interpreter who was mystified by the entire exchange. I heard a customer laughing about the difficulty of buying canned hominy at groceries that didn’t cater specifically to Mexicans. She was buying a can, so I asked her if she knew anything about using cal to create your own. She laughed, “Oh, you’re asking the wrong person! I didn’t even know you could do it yourself. Good luck!”

Naturally, I wondered how Cal compared with hardwood ash and lye as a caustic agent. I bought lye from a grocery store (near enough: drain opener containing sodium hydroxide), Cal from the Mexican grocery, and (hardwood) walnut ash from my fireplace. Then I used the cabbage juice indicator test to find out which was the most caustic. See my lesson on that subject! NOTE: lye/sodium hydroxide is EXTREMELY POISONOUS AND CAUSTIC TO SKIN.

I followed the recipe (below) for treating the corn from the website “My humble kitchen.” It confirmed what the grocery store butcher had told me. (



  1. 2 quarts organic field corn
  2. 5 tbls Lime/Cal
  3. 4 quarts filtered water


  1. Rinse corn and remove any chaff.  Drain through a colander.
  2. In a non-reactive pot, mix water and lime over high heat until lime is dissolved.
  3. Add the corn and bring to a boil for 15 – 20 minutes.
  4. Remove pot from heat, cover, and let soak overnight.
  5. The next day, drain the corn through a colander and rinse.  If making hominy for posole, remove hulls at this time. The hulls are the little brown tips which can be rubbed or picked off.
  6. Place corn in a bowl and cover with water.  Allow to soak for 5 – 10 minutes moving the corn kernels with your fingers and then rinse again.  Repeat this process one more time.  This will ensure all traces of lime are washed away.
  7. Drain the corn through a colander and you’re done.  Homemade nixtamal!

Further resources:

Here is an excellent website about niacin, vitamin B3; it’s uses, etc.

And here is a recipe for substituting nixtamalized corn meal (pre-made, masa-harina) in a cornbread recipe:

Capture Bugs with a home-made pooter

Bringing the forest to the classroom: exploring old logs with a pooter

I first read about pooters in a book by the famed English naturalist Gerald Durrell. A pooter is a tool for sucking insects into a vial where they can be observed. “Got to have one!” I said to myself. Plus, who wouldn’t love to say they’d gone pooting. A more scientific name for the device is aspirator.

Most supplies can be purchased at Tap Plastics or a brewing supply store
6 inch length of 1-inch diameter hard plastic tubing
8 inch length of flexible plastic tubing, cut into two pieces of 4 inch each
two rubber stoppers (with holes) to fit snugly into each end
small square of cheesecloth or window screen
Note: you can buy a length of hard plastic tubing and cut it on a table saw to 6 inches

Insert flexible tubing into the holes in the stoppers. Wrap the cheesecloth around the inside of one of the stoppers before shoving it into the tubing so bugs can’t get in your mouth. Put one end of the tubing over the bug you wish to observe and suck on the other end.

Pill bugs are excellent for observation, since they move fairly slowly and are easy to capture. Bring an old rotting log into the classroom and let children discover all the bugs hiding there. Bugs never seem to be injured in the process. They can be observed directly in the pooter or moved to another larger environment.

I have used pooters in many classroom and on field trips. Before I realized the importance of the cheesecloth, I swallowed at least one pill bug! However, during medieval times, people would swallow pillbugs intentionally, believing them to be medicinal; so I knew I would be fine.

A pooter similar to the one Gerald Durrell would have used