Banishing the Kingdoms November 23 2023, 1 Comment

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 

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

Sorting Branches on the Tree of Life August 07 2020, 1 Comment

Studies of the diversity of life are a pillar of life science at elementary level. In the past, Montessori classrooms used charts that show Linnaean classification – Kingdom, Phylum, Class, etc. Those charts are no longer very useful except in studies of the history of science. Instead, children need an introduction to the Tree of Life, which they can get via a branching diagram aka family tree, evolutionary tree, phylogenetic diagram, or phylogeny. If you need a Tree of Life diagram, you can download one for free at my website.

In early childhood, children sort pictures under labels, beginning with living vs. nonliving, animal vs. plant, and invertebrate vs. vertebrate, for example. Later, they sort pictures under more categories such as classes of vertebrates or phyla of invertebrates. The activity in my new material, Sorting Branches on the Tree of Life, will look somewhat familiar to children, but it has enough differences to make it challenging and interesting.

As Montessori classrooms adapt to the changing world of academic knowledge, one of the first things will be to help children learn the main branches on the Tree of Life. They need an introduction to the Tree of Life to get an overview, and then they are ready to start studying the main branches. Note that I use the terms “clade,” “lineage,” and “branch” to mean more or less the same thing – an ancestor and all of its descendants.

A challenge of Tree of Life classification is that the big branches have little branches, and the branches are not ranked (aren’t a phylum, class, etc). One simply has to know that the vertebrates are a branch of the chordates, for example. It really isn’t as hard as it sounds. Sorting Branches on the Tree of Life will help children and adults learn the main branches as they sort photos of organisms under a set of heading labels. When children have completed the diagrams, they will be able to see that the organisms belong to a number of clades. They will also be more prepared to use phylogenies (branching diagrams) that show the main branches. Older ones may even want to try their hand at drawing a phylogeny based on a diagram they have completed.  

Sorting Branches on the Tree of Life covers the vertebrates and the plants. It has a series of lessons, each of which builds on the last to help children learn the clades (branches, lineages). The lessons use images of extant animals (with one exception) and plants, but they tie into some of the history of the clades as well. One really can’t teach about the diversity of life without giving information about the origin of the branches of life.

I’ll start with descriptions of the lessons for the vertebrates in this article and leave the plants for another day. The first lesson shows the earliest branching of the vertebrates, which produced the jawless fish and the vertebrates with jaws. The latter clade, called the gnathostomes, has two branches, the cartilaginous fishes and the bony vertebrates. I have called the second branch the bony vertebrates instead of the bony fishes because it holds more than just fish. It is actually our branch as well.

The bony vertebrates have two branches, the ray-finned fish and the lobe-fins. The latter includes the coelacanth and the lungfish, as well as the tetrapods, the animals with four limbs. I used a picture of a lion to represent the tetrapods so that children could see that ALL the tetrapods belong to that lineage, not just the amphibian-like, first ones to evolve.

The second lesson shows the branches of the tetrapods, and its diagram shows that birds are a branch of the reptiles.

Reptiles, birds, mammals, and eutherian mammals each have another lesson with a diagram. The reptile and mammal lessons come after children have had the tetrapod lesson. The reptile lesson shows that this branch of life divides into the lepidosaurs (“scaly lizards”) and the archosaurs (“ruling lizards”). For the latter, the branches are the crocodilians (crocodiles, alligators, and relatives) and the dinosaurs. The pictures under the dinosaur label are a non-avian dinosaur and an avian dinosaur – a chicken. Yes, the birds are really dinosaurs, and they should be placed under the archosaur label.

Don’t panic at the idea of birds being a branch of the reptiles. We can still teach about those two branches of life separately. The traditional reptile lessons usually give the characteristics of the squamate reptiles – lizards and snakes – or of turtles, which are a world of their own, a sister branch to the archosaurs. Lessons can emphasize the traits that birds and crocodilians share. Studies of birds can note their reptile-like traits such as scaly skin on their legs.  

The mammal diagram shows the first two branches as the monotremes and the therians. This omits a lot of mammal history, but the point of these lessons is not the whole history of the organisms. It is about the branches of the currently living ones. The therians are the marsupials and the eutherian mammals, aka placental animals. When you have finished the lesson on the eutherian mammals, children can go back through and make a list of their own branches of life.

I produced this material this spring, and children in a Montessori classroom got to see a prototype just before the schools closed because of the pandemic. The teacher reported that they were very interested in the material, partly because it doesn’t look like all their other materials. By elementary age, children are ready for variety and challenge. Sorting Branches on the Tree of Life supplies both.

Spring cleaning in your biology closet March 04 2020, 0 Comments

It’s that time of year when the urge to put things in order can strike. You may have a closet with a lot of biology materials that you want to evaluate. Here are my suggestions for things to throw out. You may not want to discard the whole material just because it has flawed content provided it is feasible to fix the problems.

In the animal kingdom materials, if you find anything that has the phylum Coelenterata, please remove that name or cover it. Biologists haven’t used it for more than 30 years. That phylum was split into two others when biologists discovered that it held two unrelated groups. The two lineages are called phylum Cnidaria (anemones, corals, and jellyfish) and phylum Ctenophora (comb jellies). It is likely that you can cover over “Coelenterata” and add the label “Cnidaria.” Just make sure that you don’t have comb jellies in with your cnidarians.

Another no-no for the animal kingdom is showing protozoa along with the animals. This goes back to the two-kingdom idea of classification, and biologists and biology textbooks haven’t grouped protozoans with animals in more than 40 years.

If you find a chart that is labeled “Non-Chordates,” change the title to “Invertebrates.” Maybe “non-Chordate” was useful in the past, but biologists use “invertebrate” far more often. I searched books on Amazon.com using “non-chordates,” and I got six titles, all published outside the US. I searched “invertebrates,” and got over 6000 titles. A non-chordate chart isn’t likely to show current information, so it is time to recycle it or at least recycle the images and add new text.

The relationships between the phyla of animals solidified about 15 years ago. In biology, classification has morphed into systematics, which all about relationships and shared common ancestry. The details of this would take several blogs so I will simply say that the arthropods are related to the nematodes, and the mollusks are related to the annelids. Arthropods were once grouped with annelids, but that is no longer considered valid. Can you add something to your animal kingdom chart that shows which phyla are closely related? See my book, Kingdoms of Life Connected, for help if your animal kingdom chart needs a redo. https://big-picture-science.myshopify.com/collections/frontpage/products/kingdoms-of-life-connected-second-edition.  It is also available as an ebook (pdf).

Dig back into the cobwebs in the botany section of your closet. If your chart of the plant has club mosses separated from the fern clade – whisk ferns, horsetails, and ferns – you have a good representation of life’s diversity. The chart from InPrint for Children is a good example. https://big-picture-science.myshopify.com/collections/montessori-botany-materials/products/plant-kingdom-chart . Another mark of a current material – it should use the term “eudicots” instead of “dicots.”  If your chart has phylum names, it is quite possible that many of the names are obsolete. Many botanists no longer use phyla or division names. Instead, they use lineage names, and sometimes a common name is all you need. I have a graduate level botany textbook that uses no phylum/division names. 

If your plant kingdom chart has fungi or bacteria on it, the time has come to do some serious pruning. Those two have to go to their own charts. If the image of a fungus appears on a plant kingdom chart, that’s what children will remember even if you say that it doesn’t belong there. The fungus kingdom is a sister to the animal kingdom. In nature, fungi and plants are partners, but on classification charts, they shouldn’t hang around together.

If you have a Five Kingdoms chart, file it under the history of biology. It should NOT be the first thing children see as they study the diversity of life. The Tree of Life is the place to start.

How about your timeline of life? This is a difficult material to do well, and there are many bad attempts out there. Does your timeline show several red lines coming together (converging)? That’s the traditional style, but lineages do not converge (fuse together); they diverge (split apart). Maybe you could salvage the images and redo the timeline without the misleading lines. Check the dates for the fossils because there are several in the wrong place on the older timelines.

Does your timeline of life have photos of extant animals or plants in prehistoric times? This gives a very wrong impression. I’ve seen a timeline that had “First marsupial” and a picture of a kangaroo. This is just like saying “First eutherian (placental) mammal” and showing a picture of a horse. Both the kangaroo and the horse evolved within the last few million years. They are both adapted to live on grasslands and open shrub lands, where resources are spread out, and there is little cover from predators. Therefore both are good at moving quickly over long distances. Neither one of them belongs in the Mesozoic Era on a timeline of life. Mesozoic mammals were much smaller and less specialized.

Does your timeline have the five major extinctions? And does it have ice ages in the right places? The older charts used ice to symbolize all extinctions, although that wasn’t the cause in most of them. The five major extinctions come at the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods. They are such important shapers of life that they are essential to a good timeline.

If all this correcting sounds like too much to do, remember that you are doing it for the children. They need current information and a foundation that they can use in their future studies. There is no point in giving them science “information” that they will never see outside a Montessori classroom.

Why are updates so hard? October 28 2019, 0 Comments

How do you divide the eukaryotes? September 19 2019, 0 Comments

If I asked you how you would divide the eukaryotes into groups, what would you say? Many people would say protists, fungi, animals, and plants. This is the idea presented in Five (or Six) Kingdoms classification. There is a more enlightening way to divide the eukaryotes, one that students currently see in introductory college courses.

The DNA revolution and the development of systematics rather than plain classification have given us a new view. Systematics includes the relationships between taxonomic categories instead of listing them with no information about their shared ancestors. It is a young science that has produced many changes and will likely produce many more.

This is not to say that we don’t have useable information right now. The largest categories of eukaryotes have been defined, and they are called the eukaryotic supergroups. There are four of them presently, and so the eukaryotes can be divided into four groups. Here’s an introduction to the archaeplastida, SAR, excavata, and unikonts aka Amorphea.

Archaeplastida is the lineage that acquired the first chloroplast. Its name means “ancient plastids.” A plastid is a type of organelle in a eukaryotic cell, and the category includes the chloroplast, whose name means “green body.” The archaeplastida lineage includes red algae and green algae, along with the embryophytes or land plants, which evolved from a green alga. This lineage is the only one that incorporated an ancient cyanobacterium into its cells. The origin of the chloroplasts in other lineages is a more complicated story.

The SAR lineage is named for the three main branches within it, stramenopiles, alveolates, and rhizarians. These lineages were defined independently and then researchers gathered enough evidence to conclude that they share a common ancestor. The stramenopiles (aka chromists or heterokonts) include brown algae, golden algae, diatoms, and water molds. Alveolates include dinoflagellates, apicomplexans (parasites such as malaria), and ciliates. The rhizarians include foraminiferans and radiolarians, single cell organisms that build amazing outer shells called tests.

And where did these branches of life get their chloroplasts? It seems that chloroplasts are NOT easy to acquire. Apparently, it is easier to take one from another cell than to acquire one by eating a cyanobacterium. An ancestor of the stramenopiles and alveolates probably ate a red alga and kept its chloroplasts. Euglenas, which we meet below, got their chloroplasts from a green alga.

The third eukaryotic supergroup is the excavata, also called the excavates, but I see potential for confusion between the word as a noun vs. a verb. The lineage is named for a groove that looks like it has been excavated from the cells of some members. The excavata include the euglenas, which are free-living, and the trypanosomes, which are parasites. Other members of this group include the parasite Giardia and organisms that live in the guts of termites and help them break down cellulose. These have reduced mitochondria, so small that they were first described as lacking mitochondria.

I know you have been waiting for the last of the four supergroups, our own lineage, the unikonts (“single flagellum”) also known as the Amorphea (“having no form”). “Wait a minute,” you may be thinking, “we definitely have form.” The amoebas that belong to this lineage do not, however. The Amoebozoa lineage includes most of the slime molds or social amoebas as well as the single cell ones. Some of the latter build hard coverings (tests) for themselves. The other members of the unikonts are the fungus kingdom and the animal kingdom, which are sister kingdoms, having shared a common ancestor right before they branched off. There are other single cell organisms that are related to animals and fungi as well.

As you can see, the old protist kingdom had many different lineages of life shoe-horned into it, and the kingdoms that developed from its members were chopped off and boxed separately from it in the Five (or Six) Kingdoms scheme.

Why should you or your children learn about the supergroups of eukaryotes? It gives you a richer view of life and one that your children will see in their future studies. Will the names stay the same? Maybe, or maybe not, but these are the names in current college biology books, and it is worthwhile to learn about them and their members now.  

Enjoy your explorations of the living world!

Priscilla 

What goes on a chart of the animal kingdom? November 29 2018, 0 Comments

A chart of the animal kingdom is standard equipment for any Montessori elementary classroom. The chart could be purchased or made by the guiding adult. Either can be appropriate and useful to children. Conversely, either can have significant mistakes and misconceptions. Here are guidelines for choosing or making an animal kingdom chart.

First of all, the animal kingdom chart presents the major phyla. “What are those phyla?” you may ask. There are about 35 phyla of animals, and that is far too many to present to elementary children. Some have few members, and children are not likely to ever experience their members. The Wikipedia article on animals has a table that gives the number of species in the 11 largest phyla. Here is my list of phyla that show important structural features or notable evolutionary features. I consider the following “must haves” for the animal kingdom chart for beginning elementary.

Phylum Porifera, the sponges

Phylum Cnidaria, the anemones, jellyfish, corals, and hydras

Phylum Platyhelminthes, the flatworms

Phylum Annelida, the segmented worms – earthworms, leeches, and polychaete worms

Phylum Mollusca, the mollusks – snails, clams, octopuses, etc.

Phylum Nematoda, the nematodes or roundworms

Phylum Arthropoda, the arthropods – insects, crustaceans, spiders, and many others

Phylum Echinodermata, the echinoderms – starfish, sea urchins, sea cucumbers, etc.

Phylum Chordata, the chordates – lancelets, tunicates, and vertebrates (NOTE: Chordata is not equal to Vertebrata. The latter is a subphylum of Chordata.)

These belong on all animal kingdom charts to illustrate the range of creatures in this kingdom. There are other phyla of interest that can be added for a more advanced chart or one that spans elementary and secondary levels.

Phylum Ctenophora, the comb jellies – This phylum is significant because it is likely to be the second branch of the kingdom after the sponges. Ctenophores occur worldwide in marine waters. They were formerly grouped with the cnidarians in the obsolete phylum Coelenterata.

Phylum Rotifera, the rotifers – If children look at pond water under the microscope, it is likely that they will see these tiny animals. On a chart, rotifers would go near flatworms and segmented worms.

Phylum Ectoprocta or Bryozoa, the bryozoans or moss animals – Children are unlikely to observe these animals because they are about 0.5 mm across, but they may find bryozoan colonies at the beach. Use a guide to seashore life to identify them. Almost all bryozoans live in colonies, which can look like crusts on other organisms or rocks. Some form larger colonies that are commonly known as brown hairy tongues.

Phylum Brachiopoda, the brachiopods – These were much more common in the fossil record than they are now. The two halves of their shells enclose their top and bottom halves, whereas the two halves of a clam shell enclose the left and right sides of the mollusk’s body. This makes brachiopods a bit challenging for the beginner. I would hold this phylum for later introduction, perhaps along with studies of the Paleozoic Era.

Phylum Hemichordata – This small phylum of marine creatures includes acorn worms and pleurobranchs, which are tiny colonial animals. The extinct graptolites are placed in this phylum. Despite its name, this phylum is more closely related to echinoderms than to chordates. It is too confusing for beginners. Let children get a firm grasp of chordates before you introduce this phylum.

Other minor phyla – There is plenty for beginners to learn without adding minor phyla, however it is good to be prepared in case your children encounter an animal of a minor phylum. Many of these will be marine animals, and so a guide to marine life can be useful to place these finds into a phylum. Possibilities include ribbons worms, horsehair worms, velvet worms, and tardigrades.

Keep in mind why we are introducing children to various animal phyla. In this kingdom, each phylum has a different body plan. Children learn about the unique characteristics of each lineage. To this end, the illustrations on the chart should show at least one example that illustrates the identifying traits. Close up photos of a portion of the animal’s body or photos with a messy background or many animals together are not helpful for seeing the body plan of the organism.

Of course, the description of the phylum needs to include its scientific name. Don’t stop there, however. Children may not be able to find further information that they can read and understand unless they have common names as well. They likely know many of the common names, and it boosts learning to start with something known and move to new information.

The phylum description needs to state simply and straightforwardly the main features of that lineage. For example, segmented worms should be described as having repeated segments in their bodies. If you have a good illustration, it is easier to describe important visible features.  

Finally, how do you arrange the phyla on the animal kingdom chart? HINT: It isn’t in an evenly-spaced straight line. Some phyla are more closely related than others. The animal kingdom chart that high school or college students will see is a phylogeny, a branching diagram. If you do not wish to start with a phylogeny, you can still group related phyla together. The echinoderms and the chordates are sister phyla. So are the nematodes and the arthropods. The mollusks and annelids are another closely related pair. The animal kingdom chart from InPrint for Children is a good example of grouping phyla.

For any studies of classification beneath the level of phyla, it is best to use a phylogeny. For an example, see my material, “From the Chordates to Mammals: Exploring the Tree of Life.” https://big-picture-science.myshopify.com/collections/biology/products/from-chordates-to-mammals-exploring-the-tree-of-life

Happy animal explorations! For more information about the animal phyla and the phylogeny of the animal kingdom, see my book, Kingdoms of Life Connected.  

The Tree of Life versus the Timeline of Life March 29 2017, 0 Comments

Someone has posted my Tree of Life chart on Pinterest and suggested in the caption that it could be a substitute for the Timeline of Life. NOT SO! These are two different materials with two different uses.

The Tree of Life does not show details of life through time. It shows extant animals and their lineages. People may be confused because classification has an element of time now. We group organisms by their common ancestors. You can’t show relatives without some reference to time. My cousins and I share a set of grandparents, so we have a recent common ancestor. That’s what makes us closely related.

Classification has become systematics (more on that in a later post). Biologists do not show rows of evenly spaced boxes with no connections when they diagram a kingdom or other related life. Instead, they connect the boxes (or names) with a branching diagram to show which organisms share more recent common ancestors.

The Tree of Life chart is used much like a Five Kingdoms chart was. If you are still using a Five Kingdoms, Six Kingdoms, or heaven forbid, a Two Kingdoms chart, you need to change to a different kind of chart. A Tree of Life chart is used to introduce children to the diversity of life. When I give this lesson, I tell children that this chart has a branch for all the major kinds of life on Earth. (And you may have one precocious child who asks “What about viruses?” No, they don’t belong on the organisms’ Tree of Life. They have their own.)

I can envision directing children’s attention to the big, black branches and noting that they are all connected, and they all share a common origin. I would also say that there are many, many varieties of life, and we would have a hard time studying it all at once. Instead, we put certain branches together for the purpose of focusing on them. Three of these major branches are called kingdoms because they are all the descendants of a common ancestor. They are outlined with color rectangles – yellow for fungi, red for animals, and green for land plants. The other two rectangles show organisms that we put together for the purposes of study – purple for prokaryotes and blue for protists.

The Tree of Life is used for children ages 6-9 to show them the big overview of life. They enjoy putting the cards on the solid, colored rectangles. The text on the back of the illustrations helps children place the picture of the organism. To help them find the right place, the major section and the name of the branch are in bold typeface. Older children and even secondary level students can still use the Tree of Life, and they should have an opportunity to place the cards and discuss this chart. Do they see that animals and fungi are sister kingdoms? This is why treating fungal infections is so hard.

On the other hand, the Timeline of Life shows the organisms that have lived during the time periods of the Phanerozoic Eon. A few timelines may have a bit of the previous Late Proterozoic, but the major emphasis is on life since the beginning of the Cambrian Period. There is nothing other than a timeline of life that can show this. Unfortunately the traditional Montessori Timeline of Life is riddled with mistakes – omission of the five major extinctions, all extinctions shown as ice ages, indistinct organisms, no grouping of related organisms, and my worst pet peeve, converging red lines that seem to show several lineages being fused into one.

OK, enough attacks on the Timeline of Life. It is still an important material for children, and I think it is important to use one that is updated and corrected, either by the teacher or by a company that has carefully researched its product. The Timeline of Life helps children understand how life has changed through time. (One last rant – add the Devonian explosion of plants! During that period, the land turned green as plants changed from a low green fuzz to trees that bore seeds. The Devonian – It’s not just for fishes!)

As a reminder of what is available on my website to aid you, my Outline of Geologic Time and the History of Life has lots of information that will help you make an accurate, up-to-date Timeline of Life. The Tree of Life chart is still a free download – my gift to the Montessori community. My book, Kingdoms of Life Connected, is a teacher’s guide to the tree of life. I updated it in the fall of 2016.

May you and your children enjoy exploring the living world, both its diversity and its history.