“When any real progress is made, we unlearn and learn anew what we thought we knew before.” Henry David Thoreau

Before you read about banishing biological kingdoms, consider the cycle of learning, unlearning, and relearning. It describes what happens as we deal with new information and technologies, which we do frequently in our 21^st century lives. You are likely familiar with the learning portion of the cycle, but the unlearning part calls for some explanation.

Unlearning is NOT the same as forgetting. It is recognizing that the information you have needs to be replaced. You put your existing ideas into a different mental classification – a history archive rather than in working knowledge. For example, I quickly unlearned that the Solar System has nine planets and relearned that it has eight because I understood a new definition of a planet and why it was needed.

The first step of unlearning – recognizing that your information is not the current working concept – seems to be a hard one for many Montessorians. Dr. Maria Montessori’s stories are so dramatic and compelling that it is hard to replace them. She wanted the guiding adult to inspire children and fire their imaginations. I believe she presented her stories to show us what our goals should be, not to give information that would never change. It seems that many teachers-in-training get the idea that their albums have all the ideas they need. When guiding adults get the impression that they need to look no further than their albums, it is a disservice to adults AND to children.

Which kingdoms need to be banished?

First, I recommend that you unlearn kingdom classification schemes – the overview of life that puts all organisms into two, five, or six kingdoms. When I first began creating learning materials for Montessori classrooms, I encouraged teachers to move from a two-kingdom system to a five-kingdom system. That was appropriate advice until about 25 years ago, but now I encourage you to banish kingdom classification systems all together. Whether you use two, five, or six, send your kingdom charts to the history portion of life science classification studies.

In the early 20^th century, Montessori classrooms started with an animal or plant classification.  There are still classrooms where children see a two-kingdom classification of all life, even though biologists moved on from that concept over 50 years ago. It is time to unlearn classification based solely on the animal kingdom and the plant kingdom.  

Many classrooms present five or six kingdoms. While those five or six neat boxes are a step forward, these schemes still deprive children of a fuller view of life.  In academic studies, kingdom classification is obsolete, and biologists have progressed to a Tree-of-Life (phylogenetic) classification.   

I am still asked if I use five or six kingdoms in my materials. I answer that I use neither. Instead, I use a Tree-of-Life approach, which incorporates the three domains (Archaea, Bacteria, Eukarya). Organisms are placed on lineages based on shared ancestry. You may wonder why it matters, especially in light of my Tree of Life chart, which shows boxes around five sections of the Tree of Life.

We can certainly divide up life into manageable sections for purposes of study. That’s not the problem. The aim of our life science is to give children a mental framework that they can use now and in future studies. Why should we give only Linnaean classification and its kingdoms when biologists moved on from there long ago? There is more information in a phylogeny (a Tree of Life diagram) than in a five kingdoms chart. For example, on a Tree of Life diagram, children can see that animals and fungi are sister kingdoms (they share a common ancestor) and are more closely related to each other than either is to the plant kingdom.

You can’t see relationships between branches of life on a five or six kingdoms chart. It is a bit like the first models of atoms, which envisioned them as little solid balls. It was nice and neat, but it omitted subatomic particles, electron configuration, and lots of other information that help us understand why atoms do what they do. A five or six kingdoms chart or any classification chart that shows life in a row of disconnected boxes omits lots of important information.  

I can imagine you asking with great concern, “Do I have to take all my kingdom charts out of the classroom?” The plant, animal, and fungus kingdoms are still considered valid because they hold descendants of a common ancestor. Charts of these kingdoms may still be useful and worth children’s time, but it depends on their content and layout. Additionally, it is important that children see how these remaining three kingdoms are related to the rest of life – best accomplished with a Tree of Life diagram.

If you still have a kingdom chart for Monera, Prokaryote, Protista, or Protoctista, those need to be banished. In some cases, they may be useful if they are renamed. The first two, the prokaryotes, are now the domains Bacteria and Archaea. The term “protist” is still used as a collective term for a number of lineages of eukaryotes, but a chart of these does not show a kingdom.

The most appropriate kingdom charts group related phyla together (or even better, show the branches); They do NOT show evenly spaced rows of boxes. Here’s a quick check for your animal kingdom chart. Are the arthropods and nematodes placed together? Likewise, are the echinoderms and chordates shown close to each other? If so, your chart may be a useful one. For the plant kingdom, the fern clade (ferns, whisk ferns, and horsetails) should be placed next to the seed plants. Together, they make up the euphyllophytes, the plants with true leaves.  

My 2021 edition of Campbell Biology, a widely used college textbook, has little mention of kingdoms except on the page that shows Linnaean classification and in a discussion on the move from kingdoms to three domains. These are in a chapter called “Phylogeny and the Tree of Life. The chapter on animals is simply titled, “An Overview of Animal Diversity.” There is no mention of a kingdom in that chapter. Its chart of animal diversity is a phylogeny, an evolutionary tree (branching diagram).

Did you expect to keep teaching the same classification scheme that your life science instructors learned in their teacher education? That is not a realistic approach to science or indeed, most fields of learning. Nearly all science information is provisional, subject to revision as new information is discovered. “As best we can determine” may seem like not very good, but it is good enough to bring us our modern world with all its technological sophistication.

What is your source for current information about life sciences? Do you share your discoveries of new information with your children? A curious adult who is still learning is wonderful and a very important model for children.

So much of what we learn changes, and we have to file the old information away in the archives of our mind and realize it needs to be replaced. Our children will need to use the unlearning process. We need to model curiosity about current knowledge for our children. Most of all, we shouldn’t be giving children with the false impression that all science information is set in stone. While they may need to unlearn some information that their classrooms provide, we can strive to give them the most current, useful, and relevant ideas.  

Here are some resources to help you learn current life science concepts:

From the Understanding Evolution website: https://evolution.berkeley.edu/evolution-101/the-history-of-life-looking-at-the-patterns/using-the-tree-for-classification/

Slides from a presentation on the Tree of Life: https://www.uwgb.edu/UWGBCMS/media/Lifelong-Learning-Institute/files/Course%20Handouts/TOL-handout.pdf

Kingdoms of Life Connected: A Teacher’s Guide to the Tree of Life, 3^rd edition. Printed book - https://big-picture-science.myshopify.com/products/kingdoms-of-life-connected-third-edition. Ebook (pdf) - https://big-picture-science.myshopify.com/products/kingdoms-of-life-connected-third-edition-ebook  

Making Elementary Biology Relevant, PowerPoint slides. https://big-picture-science.myshopify.com/products/making-elementary-biology-relevant-2023

Nesting and Branching Diagrams for the Bony Vertebrates. This helps children and their guides learn about phylogenetic diagrams. https://big-picture-science.myshopify.com/products/nesting-and-branching-diagrams

Sorting Branches on the Tree of Life: Vertebrates and Plants https://big-picture-science.myshopify.com/products/sorting-branches-on-the-tree-of-life-vertebrates-and-plants

From Chordates to Mammals: Exploring the Tree of Life. https://big-picture-science.myshopify.com/products/from-chordates-to-mammals-exploring-the-tree-of-life  

Priscilla Spears

November 2023