Food, Fuel, and Fire
Transformative Adventures for Children and Their Adults
Note: This blog is a serialization of a book titled Field Trips for All of Us: Transformative Adventures for Children and Their Adults. Here is the preface. The first field trip is Taking Education Outside.
The syrup we pour over pancakes on a winter morning is summer sunshine flowing in golden streams to pool on our plates. –Robin Wall Kimmerer, Braiding Sweetgrass
Introduction
All living beings get the energy to do what we do either directly or indirectly from the sun. Plants and other green beings like cyanobacteria use the sun’s energy to synthesize energy storage molecules and building blocks. They slowly “burn” energy storage molecules to release the stored energy to grow and reproduce. Animals get the energy to perform their functions by eating plants or other beings that eat plants. Most bacteria and fungi get their energy from eating live and/or dead plant and/or animal matter. Fire, like life, releases the energy of the sun stored in plants. Fire is much faster and messier than life at doing this. In this field trip, you’ll eat the forest,work with fire, and experience how living beings store and release their energy. This field trip, like most of these posts, describes activities including discussions that you’ll probably want to engage in repeatedly over time. Each layer of experience and learning will allow for greater connections and new questions to ask!
Activity
Sharing life - giving breaths with plants: As mentioned in Observing Closed Loops in Nature, the exchange of breath between green-beings like plants and non-green-beings such as animals is one of the most amazing closed loops in nature. I like to ask kids to find a plant, stick their faces right up into it, and breathe deeply, in and out, several times. I of course model this as I’m asking. As they’re breathing, I ask them if anyone knows a story about what plants do with sunlight, or what plants make from our outbreaths, or what plants breathe out that we use. Sometimes I’ll ask if anyone knows anything about photosynthesis and help them tie that to plants and our breaths. The first thing I want them to understand is that plants use the energy of the sun to synthesize sugars from our outbreaths. Plants use outbreaths as their building blocks and energy storage molecules. They return the favor by providing us with food in the form of sugars, starches, and other carbohydrates and the oxygen they liberate from the carbon dioxide in our outbreaths.
Burning Sugar: As we mentioned in the introduction to this field trip, fire, like life, releases the energy of the sun stored in plants with results that are very similar to the results of cellular respiration. Fire is just way faster and messier than life at doing this. Sugar can be a bit slow to ignite. If you have a powerful flaming torch you can just put a tablespoon of sugar in a tin or on another fireproof surface and light it with a torch. You can also sprinkle a small amount of paper ash on a sugar cube and ignite the cube with a match as chemicals in the ash will catalyze (help initiate) the combustion of the sugar. The easiest way to burn sugar though, is to just light a marshmallow on fire. Marshmallows are basically a sugar foam set by gelatin. Just stick one on a stick in a fire safe area and light it with a match. Talk about what’s happening with your kids. What do you see? What do you hear? What do you smell? What’s happening? Where did the marshmallow go? What’s left of it?
Interpreting a diagram that shows how plants and animals provide for each others needs: The amazing thing about plants and animals is that the process that plants use to to synthesize sugars from our outbreaths and the process that animals use to release energy from sugars by slowly burning them fit together perfectly! The inputs to one process are the outputs of the other.
Plants and other green beings store energy from the sun in sugar. They do this by using light energy to put together carbon from carbon dioxide and hydrogen from water to make sugar, releasing oxygen as a byproduct. The putting together of carbon from carbon dioxide and hydrogen from water to make sugar, is called Photosynthesis. Photo is Greek for light. Synthesis means to put together.
Herbivores and omnivores including us humans eat and digest plant matter. We also absorb oxygen from the air we breathe in during respiration. We use the process of cellular respiration to release the energy plants store in sugar. This process takes place inside each and every cell in our bodies using the oxygen we breathe in to slowly “burn” sugar. Similarly, the combustion of wood involves burning cellulose and lignin as fuel in the presence of oxygen- releasing energy and water, carbon dioxide, and ash (partially combusted hydrocarbons).
Organisms that don’t photosynthesize and don’t eat plants, like mountain lions and soil bacteria, get their energy from eating other beings that eat organisms that photosynthesize or their droppings. If you’d like, you can print this page and cut out the ten words and symbols that make up the above chemical equation and practice with your kids using them to alternatively show the formula for photosynthesis and respiration. Going back and forth between the two helps us all get really clear that these two processes are just the reverse of each other! Don’t worry about your kids memorizing or even totally making sense of these chemical reactions. We’ll be returning to, and modeling this reaction during a different field-trip.
Imagining life in a 10x10 foot clear cube: I like to pose the following to kids. Imagine that you are in an airtight, room-temperature, 10x10 foot clear cube. How long do you think you would survive with nothing else but you and the air in the cube and a gallon of water? After collecting and discussing (not correcting, just clarifying your understanding of their thinking) the kids’ thoughts, I change the scenario. Imagine that you are in the same airtight, room-temperature, 10x10 foot clear cube with a gallon of water. But this time, in addition to air and water, you have a foot of great soil planted with potatoes, lettuce, and string beans, some of which are ready to harvest. Now how long do you think you would survive? Again, the first thing I do is collect their answers, possibly asking clarifying questions.
Reasoning about these scenarios benefits from some knowledge of people’s need for oxygen, water, and food and plant’s production of food and liberation of oxygen from carbon dioxide. More specifically, how long people can survive without water, how long people can survive without food, and the products of photosynthesis. I do my best to simply listen until the kids seem tapped out and then I’ll prompt again, “any other thoughts about how long you would last?” If the kids don’t mention our need for oxygen and water, or plants’ production of food and liberation of oxygen from carbon dioxide, I’ll bring those needs and products up. “Remember that people need oxygen and that plants release oxygen from carbon dioxide;Remember that people need food and that plants make food from carbon dioxide and water.”
Discussing life on a spaceship: It’s easy to expand our discussion of life in a clear cube to life on a spaceship. So, if you were going to design a multiple generation starship what would you want on the ship to support the survival of multiple generations of humans? Many science fiction stories describe spaceships as purely mechanical with magical devices for scrubbing the air and replicating food, perhaps supplemented by some hydroponic gardens. This is very much in line with Elon Musk’s Xprize carbon removal competition. Musk’s challenge is for folks to come up with ways to sequester carbon. The funny thing is, trees are already pretty damn good at that. And, because evapotranspiration requires energy, they also serve as giant cooling towers. Science fiction got me through my childhood and adolescence and we’re fans of appropriate technology, with the emphasis on appropriate. But mostly, what we would want on the spaceship would be life, and lots of it. In my conversations with kids on this topic I usually follow up my initial question with questions about what ecosystem contributors might make good additions to our passenger list.
Eating the Forest and Discussing Where Sugar Comes From: All plants produce sugar and most people love the sweet taste of sugar that can be found in plant nectars, sap, and fruit. One of our favorite activities with kids is eating in the forest. Many wildflowers contain sweet nectar that are edible for humans. I identify flowers with edible nectar by looking for what the birds and the bees are eating. Then I use field guides, Seek and the iNaturalist Citizen Science app, and the Internet to find out if the flowers of that plant are edible. If they are, their nectar will be edible, too! Honeysuckle, Roses, and California Fuschia all fit the bill. There are lots of things to learn about plant development as kids figure out the look and smell of flowers that have the most nectar. You can also use the above resources to identify edible berries in your area like black berries, wild strawberries, some honeysuckle berries, and manzanita berries.
Observing the Release of Oxygen during Photosynthesis: There’s a neat trick that allows us to watch a plant release oxygen during photosynthesis. You’ll need some fresh spinach leaves, a whole punch or scissors, a glass of water, and a hypodermic syringe to do this demonstration and/or you can watch it here. The basic idea is that you cut up little disks of spinach, pressurize them to force out gas molecules, and then put them in a glass of water to see how they release oxygen bubbles, which may float the leaf disks to the surface of the glass. During the phase of photosynthesis that happens in light (ie., the light dependent reactions), oxygen in the form of is released as a byproduct.
Discussing the Power of Fire: The ability to harness the power of fire was one of the most important discoveries of human prehistory. Like almost all human technology, fire’s utility as a source of heat and light is more than balanced by its potential to cause harm. I like to start discussions like these with mostly open-end questions connected up to activities that are meaningful to the kids. This is a discussion I like to have as we’re setting up to work with fire for the first time and I repeat some of the questions every time we work with fire.
What is fire good for? What does fire do for us? How can we use fire?
Is fire also dangerous? If so, Why?
What can we do to make our work with fire safer?
Does this look like a good spot?
Fire requires a small input of energy to get started. Once started, fires release way more energy than is needed to keep them going. This excess of energy increases the size of the fire. This is why fires, in the presence of abundant fuel, can easily get out of control. For this reason, fire safety precautions are vital. If the kids don’t come up with any of the following, I share them with the kids: (a) following fire safety regulations in your area, (b) only starting fires where the surrounding area (including above the fire) is clear of combustible materials (things that burn), (c) creating a fire circle with rocks to help contain the fire, and (d) never taking combustibles out of a fire once they’ve been in.
Building a One Match Fire: Once you’ve selected and prepared a fire-safe area you’re ready to set your kids up to practice starting a fire with a single match. I like to have kids do this in groups of two to four. I like to give them a lot of freedom. For their first try, I give them the following instructions:
Prepare your spot and call me over to check it out. Then collect your materials, prepare your materials to be lit and any materials you want to have on hand and call me over. If it looks like you’re ready, I’ll give you one and only one match, watch your initial attempt, and give you some feedback.
Nurturing fires, like many basic nature skills, requires patience. Beginning fire makers often fall victim to the “more is better” fallacy and add fuel so fast that there is not enough energy being released to keep the fire going. Like learning anything complicated, learning about fire building is an iterative cyclical process: try something, observe what happens, reflect, discuss, and try again. The big science lessons to be learned here are about using only the driest material you can find (often dead tree parts still on the tree) and starting with the smallest materials you can find (i.e., tinder) and building up to the next size up (i.e., kindling), and so on from there. See Some Nature Science, for more information about this. I also like to introduce kids to using pine sap and pitch as fire accelerants.
Starting a No Match Fire: There is plenty of information about starting fires without matches available in survival guides and on the Internet. We’re going to briefly introduce three methods here and suggest you get good at them before trying to help anyone else with them. The three methods are: (a) using a hand lens, (b) using a ferro rod, and (c) using a bow-drill.
Starting a Fire Using a Hand Lens: If you have a hand lens, find an object you want to magnify. Hold the lens between the object and your eyes at a 90° angle to your line of sight. Now move the lens back and forth between the object and your eyes until the object is in focus. Once you can do this, help children do what you did, one at a time. The details of how lenses work is a story for another time. For now, know that when a lens is used like this, it spreads out light rays reflected by small objects and projects those rays onto your retina (i.e., the “screen” at the back of your eye). That makes the object appear larger.
Now, find a spot in direct sunlight where you can clear a circle ten feet wide of any combustible material. Place a dry leaf in the center of your circle. Hold the lens between the leaf and the sun at a 90° angle to your line from the sun to the leaf. Now move the lens closer and farther away from the object projecting as small of a circle of light onto the leaf as possible.
Starting a fire with a ferro rod: Ferros rods are available at outdoor stores and on the Internet. They are a modern improvement of starting fires by striking iron against flint to generate a spark and aiming that spark at your tinder. Ferro rod is an abbreviation of Ferrocerium rod. Ferrocerium is an alloy that when struck by a hard object, generates a high temperature spark that can be used to start a fire. Again, acquire one if you can, get good at using it, and then model and guide its use by kids.
Making a Bow Drill set: Starting a fire by rubbing sticks together is an important basic skill. Ricardo Sierra uses the phrase, “the skills behind the skills” to talk about all of the skills that are prerequisite to a given expertise. In the case of starting a friction fire, these skills include finding things in the forest, basic carving skills, a feel for how to balance a fire’s need for oxygen and fuel with the amount of energy the fire is outputting at any given moment, and an understanding of, and feel for, really dry combustible wood. Bow drills are the standard for friction fires being somewhat less physically demanding than hand drills and less complicated to construct than a flywheel drill. Bow drills include four basic components: bow, fireboard, spindle, and spindle holder. Again, there’s a lot of information about using and making bow drills available in survival guides and on the Internet. I usually start by demoing using a bow drill and then giving kids guided practice time with my set. Then, I challenge them to find and craft the components one at a time with feedback from me. I suggest they start with a spindle.
Educational Suggestions
These field trip descriptions are not meant to be followed like a lab protocol: This field-trip write-up, like all of its companions, is not meant to be followed lock-step like assembly instructions or a lab protocol. When we work and play with kids the experience is way more like playing in a forest than marching through a factory. Our hope is that you’ll read these field trips through and add the described activities to your repertoire to be used as the match with the weather, your kids interests, and other factors.
Synthesizing the Indigenous and the Modern: The activities in this field trip, like those in many of the field trips in this series, include interacting with nature in ecological ways and discussing the natural world in terms of modern scientific ideas. As someone far removed from my Indigenous ancestors and culture both in terms of distance and time, this is the path most available to me as someone who is not native to this land. I am interested in learning and helping young people learn from Indigenous Elders. For us non-natives, our path must be coming to know our home land through active and intimate engagement with it.
It is important to learn whose land we are on, using native-land.ca is a great start, while also remembering that many Nations were nomadic before colonization tied them to specific pieces of land. Many of our native flora and fauna evolved with the Indigenous People of Turtle Island. Their colonization and continued genocide was the start of the downfall of many of our “wild” spaces. As Lucy Young, a Lassik and Wailaki elder, in 1936 at age 90 is quoted in Tending the Wild, “White people want our land, want to destroy us. Break and burn all our baskets, break our pounding rock. Destroy our ropes. No snares, no deerskin, flint knife, nothing”. This is why we talk with kids about asking before we take from the land. And, about asking how we can give back to the land and the original stewards. We also think it is important to learn Indigenous stories of the land, plants, and animals and help their cultures, languages, and stories continue to sing through the mountains and rivers until land back reunites us all once again.
Let your Children do Dangerous Things: Avoidance is part of our culture of separation. We avoid nature, we avoid conflict, and we avoid danger. Avoidance is a sad substitute for embracing. By attempting to avoid it, we set ourselves up for failure. Risk is a part of being alive. Our sorry attempts at protecting our children from danger only leave them unprepared to assess risk and make intelligent choices. Working with fire and tasting new things are two wonderful and risky things I encourage you to do! For more, see: 5 Dangerous Things You Should Let Your Children Do.
Sense-Making Discussions not Lecture not Silence: Not to lecture you about not lecturing but… Listening to long monologues is not the best way to learn most things for most people. Discovery without guidance is great when it happens and can be a very slow road to skillful practice and understanding. Whether learning to carve a bow-drill set or trying to understand the value of plants in ecosystems, guided engagement seems to be a productive path. We support learning fire-skills through repeated practice with interspersed guidance, moving from easy to more difficult challenges. We help kids come to understand how photosynthesis and respiration tie us and plants together in a web of interdependence by asking and discussing lots of questions (especially ones they ask!) in many contexts with interspersed guidance, moving from easy to more difficult challenges.
Many Tasks Work for Folks of all Levels of Understanding: In factory-like schools a huge amount of effort goes into matching simple, fragmented, decontextualized tasks e.g., (remember that the inputs to photosynthesis are carbon dioxide and water) to an age and ability level. Yet there is general agreement that children learn best when they are actively engaged in complex real-world tasks (e.g., starting a fire without matches). An additional benefit of working with complex real-world tasks is that such tasks provide entry points for people of all ages, abilities, and understandings.
Some Nature Science
Energy is What Makes Stuff Happen. When I talk with kids about matter and energy I say that everything is made of matter and everything that happens, happens because of energy. With older kids, I mention that matter is associated with nouns and energy with verbs. The basic story with energy is that it can not be created nor destroyed, only transformed from one form to another. The two main forms of energy are kinetic and potential. Kinetic energy is the energy of motion or more generally stuff happening. Potential energy is stored energy that has the potential to make stuff happen. For example, fire transforms potential chemical energy stored in wood into the molecular kinetic energy of heat (heat is the energy of molecules in motion, which is a story for another post). Calories are a common unit of measurement for energy. When we say that there are a few hundred Calories in a candy bar, we’re saying that the molecules in the candy bar have the potential to release a few hundred Calories of energy.
Living Beings Consume more Calories than We Use or We Die. I like to talk about the basic job of all living beings in terms of energy we take in and energy we use to do what we do. The basic story is simple. Either we take in more calories than we use to gather those calories or we burn stored calories. If this imbalance lasts, we waste away. This is why rest and doing nothing is so important for living beings in general and people in survival situations. Doing things uses energy. When energy, in the form of sunlight or food, is scarce it’s best to save energy for activities that have a chance of providing us with more energy. Using fossil fuels was a real game changer for humanity. Modern humans of the industrialized north burn huge amounts of fossil fuels in addition to the sugar we slow-burn in our cells.
Plants Photosynthesize Sugar from Carbon Dioxide and Water using the Energy of the Sun. When I talk with kids about matter and energy I say that plants use light energy emitted by the sun to photosynthesize sugar molecules. The light energy is transformed into potential chemical energy stored in the arrangement of atoms in the sugar molecule. In addition to energy storage in sugars, plants use sugar molecules to build larger cellulose, and lignin marco (large) molecules. These molecules form the structural framework of plants. This is what it means when I tell children that plants build themselves from our outbreathes.
Autotrophs and Heterotrophs: Many living beings use sugar for energy storage. Green beings make sugar from carbon dioxide and water. Herbivores and omnivores get their sugar from eating plants. Beings that can make their own sugar (or other organic food molecules) are also called autotrophs (literally self feeders) while those of us that get our energy molecules from other beings are called heterotrophs (other feeders).
Aerobic Organisms use Oxygen to Release Energy from Food: Most life on Earth uses oxygen to release the energy stored in food. Processes and organisms that use oxygen to release the energy stored in food are called aerobic. Anaerobic organisms, including anaerobic bacteria, work and play in low oxygen environments, often in water saturated environments. Some aerobic organisms including humans, engage in anaerobic metabolism under special circumstances like those encountered during anaerobic exercise.
The physical science of fire: Fire presents a fascinating area of study from many points of view including chemistry, physics, biology, history, anthropology, archaeology, literature, art, permaculture, and survival. Here, we take a look at some of the physics and chemistry of fire. In particular, we’ll answer two burning questions: Why do we need to build fires from small to large? And, why does it make sense to say that wood doesn’t burn?
There are three main forms of energy and at least three processes involved in getting fire from plant matter. The three forms of energy are potential chemical energy, light (AKA, electromagnetic radiation), and heat (AKA, thermal energy). The three processes are:
Evaporation of water: a physical change that requires an input of thermal energy (i.e., is endothermic)
Pyrolysis of complex carbohydrates: a chemical change that requires an input of thermal energy (i.e., is endothermic)
The combustion of small flammable gaseous hydrocarbons (e.g., methane) and hydrogen in the presence of oxygen: a chemical change that release thermal energy (i.e., is exothermic)
Starting a fire requires supplying a small amount of thermal energy in the form of a spark or match or lighter flame to tinder, usually in the form of a very dry complex carbohydrate with a lot of surface area (e.g., the cellulose in paper or lint). That thermal energy is enough to break some complex carbohydrates into flammable gasses through pyrolysis and to combust those gasses.
The thermal energy released from the combustion of the flammable gasses released from the tinder is enough to break some complex carbohydrates in kindling (e.g., small, dry sticks) into flammable gasses through pyrolysis and to combust those gasses. The thermal energy released from the combustion of the flammable gasses released from the kindling is enough to break some complex carbohydrates in full-sized pieces of firewood into flammable gasses through pyrolysis and to combust those gasses. At this point the fire just requires the addition of firewood to replace that which has been reduced to ash (i.e., partially combusted solid hydrogen molecules hydrocarbons with few hydrogen atoms). Under most conditions (except when wood is wet including green), combustion releases more heat than evaporation and pyrolysis take so we get to be warmed by the fire.
The balancing act to building a fire is to add new materials, and/or build a structure such that new materials come in contact with flame slowly! This slow progression from smaller to larger materials makes sure that the evaporation of water and pyrolysis of carbohydrates from the new material does not require more thermal energy than is currently available from the combustion of the flammable gasses. Small flame gets small materials going. Larger flame gets larger materials going… This is a great example of a positive feedback loop!
Understanding Feedback Loops: Under the linear causality of mechanistic logic, A causes B. In living and cybernetic systems, A causes B causes A causes B and so on. The two main forms of circular causality are positive and negative feedback loops. The feedback caused by a mic and an amplifier facing each other, painful as it is, is an example of a positive feedback loop. The mike picks up a sound (A). The amplifier makes it louder (B). The mic picks up the amplified sound(A). The amplifier makes it louder (B). This is called a positive feedback loop because the feedback increases the intensity of the original action. While positive feedback loops tend to lead to run-away systems, negative feedback loops tend to keep systems stable. For example, the furnace heats the house (A). The thermostat turns the furnace off when the temperature reaches 68° F (B). For example, the furnace heats the house (A). The thermostat turns the furnace off when the temperature reaches 68° F (B).
Wrap Up
Food, fuel, and fire; so much of humanity's story is bound up in these three little words. As heterotrophs we eat other beings as food and use the energy they stored to perform our life processes. As aerobic beings, we need oxygen to release the energy stored in food through the process of cellular respiration. Plants and other green autotrophs make their own food and release oxygen through the process of photosynthesis. These two processes fit together perfectly. The outputs of photosynthesis are the inputs to respiration and vice versa. This fit is the heart of the mutually beneficial relationship between plants and animals that has kept the amount of carbon dioxide in the air balanced for millions of years.
Fire is similar to cellular respiration. The same sugars and other carbohydrates and fats that serve as food for living beings serve as fuel for fire. Oxygen is also the partner of choice for combustion reactions involving these kinds of fuels. The use of fossil fuels for heat and light and later as a source of energy in general changed the course of human history as has thrown our global ecosystem out of balance by releasing huge amounts of carbon dioxide into our atmosphere.
Understanding humanity's relationship with food, fuel and fire, and reducing our reliance on fossil fuels is key to taking care of our global ecosystem!