Putting More Truth in the First Great Lesson August 18 2024, 0 Comments

Storytelling is a vital skill for the guiding adult in a Montessori classroom. The heart of cosmic education is the five Great Lessons/Great Stories that teachers give at the beginning of the school year. Teachers are charged with being storytellers of the truth – giving children accurate information in an inspiring way.

Truth is a slippery concept. In science or in stories that have science content, we deal with truth with a small “t”; the pursuit of Truth with a capital “T” is beyond our lessons. Scientific truth is based on evidence that scientists have gathered by observing and measuring phenomena. Scientists are able to gather more evidence as they invent newer instruments and techniques; as a result, the truth changes. Mostly, the changes are small, but that doesn’t mean they are unimportant. Note also that we cannot discount the present state of knowledge because it might change.

Recently, I received a version of the first Great Lesson, The Coming of the Universe. Below, I’m going to quote some statements from that lesson and then give my ideas on how to make them more truthful. I am referring back to this example when I write “the lesson.”

Referring to the beginning of time, the lesson says “…it was very cold…” You cannot truthfully say anything about the conditions that existed before the Big Bang. It could have been hot, cold, or something in between, but we have no evidence, so we cannot make any definitive statements. Neither can we say if it was dark or light.

The example lesson tells of tiny particles coming together to create the Big Bang. This is not how we understand the first event in the universe. I like the way the book, The Stardust that Made Us* tells it: “In the beginning, there were no elements at all. Our universe exploded into a sea of energy…” At first, there was only energy. The universe quickly expanded and cooled, and within a fraction of a second, some of the energy was converted into particles. Within minutes, the particles came together to form atomic nuclei. It was too hot and energetic for atoms to form. (An atom is an atomic nucleus with a cloud of electrons swarming close around it.) The high energy kept the electrons from the nuclei. Atoms didn’t form for nearly 400,000 years. At that time, the universe had expanded and cooled enough that atomic nuclei could capture and hold their electrons.

The lesson says, “Although this explosion occurred over 13 million years ago, our universe continues to expand.” Yes, this is a good truth for the story. After the Great Lesson, children may wish to learn more about how astronomers learned that the universe is expanding. Look for the story of Edwin Hubble’s observations of galaxies.

The lesson goes on – “Within a few minutes of this explosion, all the matter in the universe was formed.” Not quite – energy can be transformed to matter, although we are more familiar with the opposite. Our Sun and all stars convert matter to energy, which is what keeps them from collapsing under the force of gravity. All of the matter AND energy of the universe came into being then.

The lesson implies that all the early matter was in the form of a gas. This is not true. At those temperatures, matter is in the plasma state. It is a sea of bare atomic nuclei, free electrons, and various other particles. It is important to get this right. Here’s a better version.

In the beginning, the first atomic nucleus to form was hydrogen. In the very hot, dense, and energetic conditions, some hydrogen nuclei collided and formed helium. There were also teeny tiny traces of lithium and possibly just a few other elements – all of which were less than one-billionth of all matter. Almost all the matter was hydrogen and helium. That’s what scientists observe today when they look at the stars – they are mostly hydrogen and helium. After this, the universe was too cool for atomic nuclei to smash together and form new elements. It would take special conditions found only in a very special place to make other elements.

The lesson says that as the universe cooled, the particles came together and formed stars, planets, moons, asteroids, etc. There is more to the story, and it is not too complicated for children to understand.

There is only one thing that can be made from hydrogen and helium alone, and that’s a star. Stars are made of enormously huge amounts of atoms. Gravity pulls the atoms together until the star’s center is very hot and dense. Astronomers think that it took an extra huge amount of hydrogen and helium to make the first stars. These giant stars burned their hydrogen and helium fuel quickly. Gravity pulled their matter together very compactly, and that made their centers very, very hot. These conditions squeezed the atomic nuclei together and formed larger elements. Some of the matter converted to energy, like it still does in stars. Now you know the special place where elements other than hydrogen and helium form. It is the amazing furnace inside the stars that gave us the elements that form planets and life.

As the first stars died, they spread new elements into space, and this helped further star formation. With some different kinds of atoms mixed with the hydrogen and helium, smaller stars that lasted longer could form. Our Sun is likely a third-generation star. It has a bit less than 2% of its mass as elements other than hydrogen and helium as compared to less than a billionth in the first stars.  

One of my favorite children’s science books, The Horse and the Iron Ball** explains the origin of elements very well. It is a bit outdated, as astronomers now know of other cosmic events that produce heavy elements. The basic story is still good and still inspiring.

I will write more about the formation of our Sun, the Earth, and the Moon another time. This is a big enough bite for now. Please feel free to add your questions and comments.

* The Stardust that Made Us: A Visual Exploration of Chemistry, Atoms, Elements, and the Universe. Written by Colin Stuart, illustrated by Ximo Abadia, published in 2024 by Big Picture Press (no relation to Big Picture Science.)

**The Horse and the Iron Ball: A Journey Through Time, Space, and Technology. Written by Jerry and Georgiana Allan, illustrated by Jerry Allan, published in 2000 by Lerner Publications Company.

Banishing the Kingdoms November 23 2023, 1 Comment

Plant to support Nature – We can do this! May 17 2023, 1 Comment

Almost all classrooms have the ability to grow plants outside, even if it is only in containers. Many schools have extensive grounds. Some fortunate schools are surrounded by a natural area, but frequently, the landscape is mainly ornamental plants that are native to other regions. How many of the plants around your school are from your local ecosystem? This is an important question to address.

Humans have taken over a significant part of our planet. Our buildings, lawns, roads, and fields exclude the native plant communities and all the animals that rely on them. It is heartening to know that this is a problem that we can address simply by what we choose to plant. We can give important support to insects, birds, and other life in our native ecosystem. It is good for all the life of our ecosystem – including us.

Children can learn about what we can do from the Young Reader’s Edition of the book, Nature’s Best Hope: How You Can Save the World in Your Own Yard. It was written for adult readers by Douglas W. Tallamy and adapted for younger readers by Sarah L. Thomson. Older elementary and middle school children can read this book to learn about the problem and ways to help.

I learned important ideas from this book. I knew that we need to grow plants that support pollinators with nectar and pollen. I had not fully grasped the need to plant host species for caterpillars. These plants are vital to the insects’ survival, but beyond that, they play a huge role in the support of bird populations. It is because of the food baby birds eat. They cannot feed on the seeds or adult insects that their parents consume. Instead, they need soft-boded caterpillars, and their parents have to find thousands of these insect larvae to raise a nest full of babies.

How do we find plants that support our insects and birds? The National Wildlife Federation is a good source of this information. See https://www.nwf.org/Garden-for-Wildlife/About/Native-Plants. This website features a native plant finder. You enter your zip code, and it gives you lists of plants that host the most butterfly and moth species. These plants will help provide food for the birds in your area.

What is in our gardens now? Many of the ornamental species we grow come from other parts of this continent and even from other continents. People love to have a variety of plants in their gardens. We don’t have to get rid of all our exotic species; we can add native plants. A good goal is at least half in native plants.

The lawns in the US take up an amazing area. Tallamy writes that in the state of Maryland, there are twice as many acres in lawns than in all state parks, state forests, and wildlife management areas put together. It is the same in most Eastern states.

Schools need playing fields and spaces for children to run and exercise, so it isn’t practical to get rid of the grass. All of the area around the school doesn’t have to be a lawn, however. A border or corner can be set aside for native plants. Areas that get little foot traffic can be changed to a meadow of mixed native plants, very attractive to people as well as insects. Less grass means less water for irrigation and less mowing and fertilizing. Cutting back on fertilizer is important for greater ecosystem health because fertilizer runoff promotes harmful algae blooms and lowers drinking water quality.  

The University of Florida Thompson Earth Systems Institute has information about the importance of insects and what we can do to help rebuild their populations, which are declining. See https://www.floridamuseum.ufl.edu/earth-systems/the-insect-effect/. This website has guidelines for making your outdoor spaces insect friendly. The decline in insect species and numbers doesn’t make headlines like other climate problems, but it is a critical one to address.  

Beds of flowering plants offer many possibilities for botany studies, including pollinator watches, observations of bud formation, finding flower parts, and watching fruits develop. Diversity – having many different species – is important for survival of ecosystems. Children can compare the life they see in a flower bed planted with many native species versus a grass lawn. So many good learning experiences await in a richly planted landscape!

Moving Beyond Three-part Cards February 13 2023, 0 Comments

In the early childhood Montessori classroom, the three-part card is a mainstay. For the youngest, this material consists of an illustration with its name plus the illustration and name on two separate cards. Later on, the set includes a brief description or definition. Children build their vocabulary and reading skills with these cards during the ages when acquiring language is a prime interest.

What about elementary children? I have heard from several elementary teachers that children lose interest in three-part cards in their elementary years. They are past the time when they are interested in learning words for words’ sake. If they attended a Montessori school prior to elementary, they likely had the opportunity to work with three-part cards frequently. They may be ready to move on to something new.

Upper elementary teachers have told me that their children are drawn to card sets that have more challenge and require them to figure something out. With this in mind, I designed my latest card set, What Fruit Is Growing Here? It challenges children to match photographs of flowers and the fruit that develops from their ovaries. There are 16 species shown in this set; it includes a text card for each species that tells its lineages, botanical features, and name origin. https://big-picture-science.myshopify.com/products/what-fruit-is-growing-here-file-for-printing. The printed version is available at https://big-picture-science.myshopify.com/products/copy-of-what-fruit-is-growing-here-printed-cards. 

What Fruit Is Growing Here? is similar to my previous set, What Flower Is Growing Here? https://big-picture-science.myshopify.com/products/what-flower-is-growing-here-printed-cards and https://big-picture-science.myshopify.com/products/what-flower-is-growing-here (file for printing). The first set has photos of buds and the flower that blooms from them.

I got the idea for these two botany sets from my zoology set, Whose Foot Is This? https://big-picture-science.myshopify.com/products/whose-foot-is-this  It shows photos of mammal feet and the animal that has them. Here is an excerpt from a review of this zoology material by master Montessori teacher Jennifer Spikner: “The lower elementary students at my school absolutely LOVE this material! The photos are high quality and the text is well written and really interesting. Because of the number of cards, it feels like a puzzle, which the students find really engaging. ... My students learned so much about how mammal feet are adapted for their needs- and they truly enjoyed it!”

How many times have your children (or you) truly enjoyed botany cards? My goal is to make botany studies fun and engaging. Observing buds and seeing flowers emerge from them is a gift that children should have, and the What Flower Is Growing Here? set prepares them to receive that gift. Likewise, the flower-fruit-seed sequence is a major concept of botany that we should help children grasp. The What Fruit Is Growing Here? set illustrates many variations of flowers and their fruits with the goal of helping children observe fruit formation in real plants.

Right from the start, when you study fruits, you will need to clarify the distinction between culinary fruits and botanical ones. It would be much easier if English had two different words for these like Spanish does. “La fruta” is the sweet and juicy thing we eat, and “el fruto” is the structure that develops from the ovary of a flower, whether it is sweet or dry and brown.

The What Fruit Is Growing Here? set shows children a wide variety of fruits, examples from various categories. The teacher background information includes a chart of fruit classification by structure. There isn’t a single widely accepted method for classifying fruits, and they are not classified by common ancestry. Botanists often start with three categories – simple, aggregate, and multiple fruits. Simple fruits form from the ovary of a single flower that has one carpel or pistil. Aggregate fruits form from a flower that has several distinct carpels, each with their own ovary. Multiple fruits form when the ovaries of several flowers fuse together into one structure. Botanists divide the simple fruits by their moisture level at maturity – dry fruits vs. fleshy fruits. There are several categories of simple fleshy fruits and simple dry fruits. They are not something to memorize, but children can be aware of them and understand them.

I hope that work with my What Fruit Is Growing Here? card set will lead (or follow) work with real fruits, some from the grocery store and others from the garden, weed patch, or wherever there are nearby flowering plants.

Enjoy your botanical explorations!

Priscilla

What’s New in the Third Edition of Kingdoms of Life Connected? January 12 2023, 1 Comment

Last fall, I completed the third edition of my book, Kingdoms of Life Connected: A Teachers’ Guide to the Tree of Life. This came only six years after the second edition, which in turn came eight years after the first edition. “Why all this change?” you may ask.

I found that updates were needed because of changes in biologists’ view of the diversity of life. The data about how organisms are related continue to pour in, and because of this, the details of lineages and relationships change. You may be tempted to wait until the field stabilizes and stick with older ideas. Children, however, need a useful view of the diversity of life, even if it will be somewhat amended later. They cannot build on a foundation that is clearly obsolete. Specifically, it is no longer useful to present children with Five or Six Kingdoms, and those charts need to go in your history-of-science file.  

I updated Kingdoms of Life Connected from cover to cover. I redid the lists of learning resources – books and websites; I purged links that no longer worked and added new ones. Publishers and authors have brought forth valuable new books in recent years, and I added titles to the lists while retaining older but useful books. I revised all the text, including the activities and lesson suggestions. I fact-checked the information to make sure it was as up to date as I could make it.

There is one especially important addition, a new lesson for introducing to the Tree of Life chart to beginning elementary children. This lesson gives older children important concepts as well, particularly if they have not yet had this overview. The introductory lesson leads children to the idea that all life shared a common ancestor and is connected. It shows them the relationships between the major branches of life. For example, they learn that the animals and fungi are sister lineages and that plants are only distantly related to fungi.

I’ll give a brief summary of some of the changes below. For more information, see the book, which is available at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition (printed version). The ebook (pdf) is at https://big-picture-science.myshopify.com/collections/biology/products/kingdoms-of-life-connected-third-edition-ebook.

There are no big changes in the prokaryotes. I have kept a very basic approach because it takes extensive knowledge of biochemistry to understand the many branches of bacteria and archaea. Introductory college biology texts present a few basic lineages, and I felt that this approach would be good for children as well.  

In the protists, I rearranged the Excavata lineage on the Tree of Life chart. Now, the euglenazoa and kinetoplastids are sister lineages and the metamonads are the first branch. I expect that Excavata will be split apart and redone in the future. It probably won’t be a eukaryotic supergroup, but studies continue to confirm the other supergroups – Archaeplastida, SAR, and Amorphea.

Scientific terminology evolves, and I was happy to see a complicated name go away. The branch of the stramenopiles and alveolates was previously called Chromalveolata, but that term has fallen out of favor. It originally described a lineage that included two branches I didn’t show, the cryptophytes and haptophytes; these are now placed elsewhere on the Tree of Life. The branch of the stramenopiles and alveolates may get a new name, but it seems best to leave that branch blank for now.  

The fungi were the major branch that changed the most. The former Zygomycota lineage is now divided into two main lineages, the Mucoromycota and the Zoopagomycota. On my Tree of Life chart, I show the larger one, Murcoromycota. Its branches include the pin molds or Mucoromycotina (black bread mold, for example) and the arbuscular mycorrhiza fungi or Glomeromycotina (AM fungi). The AM fungi were previously placed on their own branch, but they have been added back to Mucoromycota. I didn’t add the Zoopagomycota to the Tree of Life chart, but if you have children who are interested in learning more, Fungarium by Katie Scott and Ester Gaya, is a good book for launching their explorations.

In the animal kingdom, studies have clarified some relationships in the protostome branch. You can give children the term “Spiralia” for the lineage previously called Lophotrochozoa. The whole branch is called Spiralia; “Lophotrochozoa” still refers to the mollusks and annelids. It is another of the situations where it is useful to know an older and newer term. “Lophotrochozoa” has been used for the Spiralia branch for about 20 years, and it appears in a number of websites. I recommend looking to the future and using “Spiralia” primarily. It is certainly easier to say and spell.

In the plant kingdom, studies have resolved several questions about the bryophytes. They are a single branch of life, a monophyletic lineage. The first branch was recently determined to be the hornworts. The mosses and liverworts are sister lineages. The older story was that the liverworts were the first branch because they do not have stomata. It appears that their ancestors lost their stomata rather than never having them.

The virus chapter now has suggestions for making a model of a coronavirus. I published this chapter as a stand-alone pdf in 2020. Note that if you have the third edition of Kingdoms of Life Connected, you already have the content of “What Is a Virus?”.

It is easy to become overwhelmed by all the names and branches of life. I recommend that you concentrate on the larger branches on the Tree of Life and continue to other branches as children (and you) learn about these and are interested in pursuing more. For in-depth studies at the elementary level, I recommend the digging further into the animal and plant kingdoms.

Start with the big overview of the Tree of Life. After that, my learning material, Sorting Branches on the Tree of Life: Vertebrates and Plants, is a good place to go. It is available as a pdf that you can print https://big-picture-science.myshopify.com/collections/biology/products/sorting-branches-on-the-tree-of-life-vertebrates-and-plants or as a printed material https://big-picture-science.myshopify.com/collections/biology/products/copy-of-sorting-branches-on-the-tree-of-life-vertebrates-and-plants-file-for-printing.  

Enjoy your explorations of the Tree of Life!  

The Gorilla in the Montessori Room July 15 2022, 2 Comments

What is this about a gorilla in the Montessori room? Is it a radical new classroom pet?

No, it is a symbol of an ongoing problem that is being ignored for many reasons – it is difficult, uncomfortable, and so big that it will take considerable effort to deal with it. Here is why I think there is a “gorilla” in Montessori classrooms.

Maria Montessori designed her brilliant elementary framework around five great lessons, and she constructed it with her perspective as an early 20^th century European. Her understanding that children need spiritual nourishment, not just facts, guides us today. Her stories are tied into the science content she felt children should have. She gave them real knowledge, not a watered-down version, along with inspiration to learn more.

The inspiration and spiritual nourishment are still wonderful, but there is a problem with the content of those stories and the lessons that come from it. She used the state-of-the-art information for her time in the stories, and many classrooms still do that – they use the state-of-the-art biology from the mid-20^th century. This leaves children woefully out of touch with today’s view of life science.

Biology has come a long way since the mid-20^th century. Not only are two, five, or six kingdoms obsolete, but the whole idea of kingdoms is not what it once was. If you still use five or six kingdoms as your main lesson on the diversity of life, it is time to move those materials to the history of biology and move on. The Tree of Life provides the framework now, and the three kingdoms (fungus, animal, and plant) that are still valid are not the organizing framework for the diversity of life. Instead, they are major branches among many others on the Tree of Life. Biologists have extended classification to include the relationships between all kinds of life. Shared common ancestry drives classification, not just physical appearance.  

For an example, see the website for animals, The Shape of Life: The Story of the Animal Kingdom (https://www.shapeoflife.org/). It has a tree of life that gives the derived traits for the lineages. You can download the pdf from https://www.shapeoflife.org/news/resource/2016/10/18/tree-life and print it. This branching diagram is not for beginners, but it will help you see how the diversity of life is shown scientifically.

This website also has an artist’s Tree of Life for animals, and I think children would enjoy poring over it. It is by Ray Troll; the pdf is available at https://www.shapeoflife.org/news/featured-article/2018/02/26/we%E2%80%99ve-got-your-tree-life-right-here. Even though it is an artist’s interpretation and shows little of the other branches of life, it has valid branches for animals.

There has been such a revolution in biologists’ ideas about the diversity of life that it has required college professors to be flexible and ready to change. Some revise their course content on a yearly basis. DNA data has been a big part of the change, and biologists continue to acquire new data. The rapid change doesn’t mean that it is OK to stick with old ideas until the field settles down. It means that children need the new framework and new ideas about how biologists see life’s variety. They don’t need to spend time learning a system they will set aside in further studies.

Back to that “gorilla.” I see that inadequate movement toward new ideas is common in Montessori teacher education programs. The extent of change in biology means that everyone needs to learn current biology ideas, including teacher educators and teachers with all levels of experience. It calls for relevant conference presentations and professional development courses. It means that teachers can’t simply change a few terms and keep teaching the old framework.

Certainly, there has been progress in updating biology for Montessori schools. Cynthia Brunold-Conesa’s album, Life Science Lessons for Montessori Elementary Classrooms, has a totally new structure and current ideas. You can find it at https://georgeconesa.wixsite.com/lifesciencemont. 

For more than two decades, I have been working to bring updated materials with current ideas to Montessorians. My recent video course, Life Science Literacy for Elementary Teachers, is available through Trillium Montessori at https://courses.trilliummontessori.org/p/life-science-literacy. I have revised my books and card sets multiple times, and I continue to do so each time I reprint an item. The websites change, the classifications change, and even the terminology evolves.  

Montessori classrooms help children acquire knowledge. In biology, will it be useful knowledge, or will they have to relearn the subject later? It depends on whether Montessori leaders do something about that gorilla in the room. 

Priscilla Spears, July 2022 

Teaching about Change, Climate and Otherwise February 05 2022, 0 Comments

“There is nothing permanent except change.” – Heraclitus

The last two years have been full of changes, and it is sometimes hard to adapt quickly. Children need to know that change is a characteristic of our planet and of life. There is a new book that helps with this concept. All Things Change: Nature’s rhythms from sprouting seeds to shining stars by Anna Clayborne and Sarah Edmonds (2021) tells about change on many scales. It starts with the Big Bang and looks at seasonal and daily changes in the cosmos. It shows life cycles and changes in people, too. And it introduces the change that is so challenging to us, climate change. 

Natural cycles of change – day and night, phases of the moon, the tides – are comforting and familiar. Climate change is quite the opposite. All of us are impacted by it, some in small ways but many in very major ways. Children need to know what is happening and what they can do to help. This is not a subject to ignore, but rather one to prioritize.

To understand why climate change is such a problem now, one needs to consider the rate of change. It might help children to imagine this with a story about changes in their classroom. What would it be like if their daily schedule changed frequently, and they didn’t know what to expect? What would it be like if materials were in a different place each day? It would be confusing, and children would spend a lot of energy figuring out what is going on. Animals and plants whose environment is changing have lots of stresses, including not being able to find enough food and having extreme weather events like droughts, heat waves, and extra strong storms.

There is a productive place in between despair and denial, and that is where our lessons and books need to be. Some of the books I read were so heavy on the doom and gloom that I felt they would produce more paralysis than action. Others brought the hope of people working together in a variety of ways.

It is always good to start with factual information. For this, I like a World Book publication, Understanding Climate Change, from the Earth’s Changing Climate series (updated 2019). It lays out the basics of the greenhouse effect, and it brings up a number of ideas about why the Earth is warming. It provides evidence that the magnitude of change that we are seeing is not because of volcanos or variations in the Sun, but rather, it is because of humans burning fossil fuels and releasing other greenhouse gases. This series is for upper elementary and middle school levels. You can preview it online. 

For beginning elementary, the book, The Story of Climate Change: A first book about how we can help save our planet by Catherine Barr and Steve Williams is a good introduction. It begins with the early Earth and tells about climate change throughout our planet’s history.

You may need to help children understand that “save our planet” really means “save the biosphere.” The Earth will keep on rotating on its axis and orbiting the Sun no matter what humans do. The tides will continue each day no matter the sea level. It is the biosphere that is being threatened by climate change.

Children need to know that they can take actions that help with climate change, but I would not want them to feel like they have to fix the whole problem. It is, however, important for everyone to do what they can to make constructive changes in their everyday life. Some have voluntarily taken extensive actions, and their stories can be inspiring. Old Enough to Save the Planet by Loll Kirby and Adelina Lirius tells the story of twelve children from around the world that have done something to counter climate change. The children and their projects are diverse, and their stories lay out a range of possibilities.  

Climate change is directly related to how we use the resources of our planet. One of the pressing problems is with plastics and waste. A Portuguese marine biologist has written a book with a creative approach to the problem. She decided to treat plastic like an invasive species, so she gave it a Latin name that is also the title of her book.  Plasticus maritimus: An invasive species was written by Ana Pêgo and Isabel Minhós Martins and illustrated by Bernardo P. Carvalho. This book tells the story of the main author and her efforts to clean up the beach. It has lots of good and interesting information about plastics and the environmental problems they cause. It also tells about alternatives to plastic and the places where laws have been passed to limit the use of plastics. 

The problems of climate change and the use of plastics will be with us indefinitely, but that is no reason to ignore them. I hope that you and your children will find uplifting stories and productive ways of making progress on these problems.  

Teaching accurate evolution concepts is important for people and the planet November 08 2021, 0 Comments

I have been studying the concepts of evolution and false ideas about this process. “Evolution” literally means “unrolling,” and we use the word as a name for the changes in life over time. I am convinced that children (and everyone else) need to know valid ideas about evolution as a basis for social justice and peace.

The idea that some life is more advanced or important than other life started with Aristotle and Plato. They used an animal-vegetable-mineral classification, which is an intuitive idea that still exists. It leads to misconceptions about how evolution occurs and what it produces.

Aristotle introduced the “scala naturae” or great chain of being, which is a ranking of organisms from “lower” to “higher.” He ranked animals with blood above those without – the invertebrates whose blood he didn’t recognize. Plants, of course, went beneath animals, followed by minerals. Soil was at the very bottom of the scheme, which is the opposite of our current view. Now we see soil as a unique combination of living and non-living, and the foundation and sustainer of life on land.

During the Middle Ages, the idea of a chain or ladder of life became a religious idea as well. At the top sat the deity with the angels beneath, then humans, and so on down the ladder. Religious authorities presented this ordering as divinely given, which likely helped keep those on the lower rungs of social structure down there doing the hard work.

At one time, biologists used the great chain of being concept, and scholars thought that all organisms were striving to improve and move up the ladder of life. When Darwin proposed his theory of evolution via natural selection, he included the idea that there was no direction to evolution. After genetics and molecular biology showed the mechanism of evolution, most biologists accepted the idea that evolution doesn’t have a goal. Some biologists still thought that life was evolving toward complexity or some pinnacle of evolution.

One of the most famous – and wrong – illustrations of evolution shows a monkey, an ape, a caveman, and a modern man marching along from left to right. Note that I said “man” not “human.” This iconic illustration always ends with a Caucasian male. It leaves the impression that white males are the ultimate product of evolution.

There is no pinnacle of evolution, only a many-branched Tree of Life. There are no “highly evolved” organisms vs. more primitive ones. All life in existence is very complex; it has thousands of molecules in a highly ordered arrangement, all functioning together. All extant life has been evolving for the same amount of time although some lineages have undergone more visible changes than others. If life continues to exist, it continues to evolve.

It may seem that evolution produces more complex life, but that is not always the case except for the earliest life. Think of life starting as simple cells. There wasn’t any room to get simpler, but the opportunities to become more complex were plentiful. Even with that, there are many instances of a lineage of life becoming less complex and losing structures rather than developing new ones. This has happened frequently with parasitic organisms, but free-living animals also give up structures. The echinoderm lineage is sister to the chordates, which means that they shared a common ancestor. One branch got more complex and developed vertebrae; the other got simpler and combined several organ systems into a water vascular system. Both are highly successful.

As far as anyone can tell, evolution has no special direction and no goal other than the survival of life, all kinds of life. Especially all kinds of life because it takes diversity for life to continue. There is no climbing to the top, whatever that might be. With no ladder of life, there are no missing links, and paleontologists no longer use that term.

What does this mean in the classroom? The guiding adult must take great care to express the concepts of evolution accurately and to remove any diagrams that give false impressions.

I’ve written previously about the problem of teleology, the idea that organisms change because they want to or need to do so, but it is worth repeating. Fish didn’t decide to try growing legs, and they didn’t get them because they wanted to get out of the water. Those are teleological ideas. If an organism could change because it wanted to do so, there would likely be a lot of three-armed people taking care of small children. 😊

I don’t mean to say that people can’t change; they certainly change their minds and may work to bring about other changes in their lives. Individuals do not evolve, however. Evolution can be defined as a change in the frequency of a trait in a population. The process of natural selection brings about this change. A random mutation can change a trait in an individual organism, but evolution doesn’t take place unless that trait is passed to offspring, AND it confers an advantage for surviving and reproducing.

In the classroom, if children see a Tree of Life diagram that shows humans (or mammals) as a part of the diversity of life, they will have a better perspective than if they see a row of equally spaced boxes with humans/mammals at the far right. If they see a timeline of humans that shows modern humans with a range of skin colors, it will give a more accurate impression of what the evidence indicates has happened. An accurate timeline of humans cannot be a straight line. See https://humanorigins.si.edu/evidence/human-evolution-interactive-timeline for a more realistic view.

A timeline of humans that ends in light-skinned and light-haired people is not fair to anyone. I think it is best if children understand that there are many colors and cultures of humans, and that all of them are equally evolved and equally valuable. You may ask best for what? Best for our species and the whole biosphere.

“Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress.”

― Stephen Jay Gould, Wonderful Life: The Burgess Shale and the Nature of History

Priscilla Spears, November 2021

Why Montessorians need a new biology album July 28 2021, 0 Comments

Make Your Own Timeline of Life April 23 2021, 1 Comment

The Timeline of Life, with its starring role in the Coming of Life Great Lesson, is an important material for elementary Montessori classrooms. Teachers must either purchase one or make their own. The commercially available ones all have issues, which make some of them undesirable for the classroom. See my previous blog article, What goes on a Timeline of Life? for the details. That’s the bad news.

The good news is that making a Timeline of Life isn’t as difficult as it first appears. It is a timeline of the Phanerozoic Eon. Here are the measurements for a timeline that is three meters long. On it, 1 cm symbolizes 2 million years. The Phanerozoic Eon itself takes up about 2.71 meters. The extra length allows you to add the late Proterozoic Ediacaran biota and gives you a border at the ends of the chart.  

Timelines are much more than just a time scale. This one needs illustrations of life and how it has changed over time. I was happy to find that the United States Geological Survey (USGS) has a great source of these illustrations online. In 2020, a physical exhibit called “Trek Through Time” opened at the USGS headquarters in Reston, Virginia. That exhibit is also available online at https://www.usgs.gov/science-support/osqi/youth-education-science/trek-through-time. It is illustrated with posters for each time period. Here is an example, the poster for the Ordovician Period.  

Click on the “Let’s Take a Walk” link to access the posters for the time periods. These high quality illustrations are in the US public domain, and you can print them for your classroom. Click on the thumbnail illustrations of each poster to get the files for printing. Select “original” to get the largest size, which can be printed on letter-sized paper. These posters have a small world map inset that shows the land masses at that time. A red dot marks the location that will become Reston, Virginia. The description of each time period has information about the biota of the Earth, how our planet looked, and what its climate was like. It also gives conditions in Virginia at that time. This information would make good text cards to go with the posters.

For the Ordovician and Silurian Periods, the poster is wider than the time period. For the Cenozoic, the six posters will have to be stacked one on top the other because each of them is about as wide as the whole era.

The Trek Through Time posters are a good start to a useable, up-to-date timeline of life. You can add organisms as the children explore prehistoric life. When children see a dynamic timeline develop as they add their own contributions, it can be more engaging than working with one that is all done for them. Adding new fossil discoveries can be especially inspiring. 

If you have good illustrations of animals from an otherwise not-so-great timeline, you may be able to use them on your new timeline, but carefully read and verify any information on cards for the organisms and make sure that you place them in the correct time period. Wikipedia can be a great help in finding when an animal lived if you have a name it.

Illustrations of plants from older timelines are usually not worth keeping. There are good black-and-white drawings of ancient plants at the Virtual Paleobotany website, https://ucmp.berkeley.edu/IB181/VPL/Dir.html. You can also find illustrations in books on fossil plants and plant evolution, which you may be able to get from a library.

What about all those red lines that appeared on the original Montessori timelines? I recommend that you leave them off unless you can connect organisms in valid lineages. If you can’t stand back and see meaning and pattern in the lines, they are likely to distract rather than give a useful impression. Certainly, you should not have any lines that come together. The Tree of Life branches out.

Add the five mass extinctions by drawing a thicker black line after the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods. These events have been major factors in the shaping of life on Earth. 

If you and your children are interested in learning more about mammals after the dinosaur extinction, my new material, The Story of Mammals: From the dawn of life to the present day, has instructions for making a Cenozoic timeline that is long enough to show the many changes in mammals in the last 66 million years. This set includes the file to print 84 picture cards to place on the timeline and a 76-page booklet of lessons. You can see it at https://big-picture-science.myshopify.com/products/the-story-of-mammals.    

I hope that you and your children enjoy your explorations of life through time.