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What impressions of plants are we giving? Part 1. The needs of the plant. June 12 2019, 1 Comment

I have been looking at these charts and asking myself what else children today need to know about plants, and whether everything shown on the original charts is still considered valid. 

A chemistry chart that IS NOT the periodic table February 13 2019, 0 Comments

We all know and use the periodic table. This icon of chemistry classrooms has many versions. The chemistry community is celebrating the table’s 150th anniversary this year. You can see the latest version of it here: https://iupac.org/what-we-do/periodic-table-of-elements/ . If you would like to know more of its history, see https://www.sciencenews.org/article/periodic-table-history-chemical-elements-150-anniversary.

All elementary and higher classrooms need to have this chart. I recommend that you start with a simple version that has the elements’ symbol, name, and atomic number but little else. That’s enough information for beginners. The color scheme should make it easy to tell the metals, metalloids, and the nonmetals apart. Samples of some common and safe elements will help children see the significance of this chart.

My card set, “Discovering the Periodic Table”, helps children find out why the elements are arranged as they are on the periodic table. You can see more about at https://big-picture-science.myshopify.com/collections/physical-science/products/discovering-the-periodic-table.

I like to tell children that if they meet an alien from another planet, they could communicate via the periodic table because the chemical elements are present throughout the universe. We can tell this by the unique wavelengths of light that each element gives off.

After children are familiar with a simple periodic table, they may find a chart that illustrates the elements attractive. These charts vary in quality, and most are confusingly busy. Make sure that an illustrated chart shows something that is meaningful to children or that it shows the actual element. Vague scenes or unfamiliar objects are not likely to help children grasp the concept of elements.

There is another chart for chemistry that is very useful for advanced elementary and middle school levels. It is the classification of matter chart. If you search the Internet for “classification of matter chart,” you will find many flow charts. Big Picture Science offers the chart from InPrint for Children, which I helped design. This chart shows the chemical forms that matter can take. First, it divides matter into pure substances and mixtures. It has four photo cards with information on the back for each of four categories – elements, chemical compounds (both are pure substances), and homogeneous and heterogeneous mixtures.

This chart has information that children need to imagine the kinds of atoms or molecules that may be in a substance. They see how chemical elements are a part of all matter and how elements combine in compounds. Most matter that they encounter is some sort of mixture. The chart will help them sort out the major types of mixtures as well.

The photos show four common elements that you can have as samples in the classroom – zinc, copper, sulfur, and silicon. The latter is available from scientific supplies as the lump form, laboratory grade. Be sure to get the lump or crystalline form. This element is also sold in a powder form, but this doesn’t allow children to see the shiny crystals.

Enjoy exploring the chemical elements and ordering them on the periodic table and the classification of matter chart!

Priscilla 


What goes on a plant kingdom chart? December 27 2018, 0 Comments

Like its counterpart, the animal kingdom chart, all Montessori elementary classrooms need a plant kingdom chart. A current version of this chart will have the same elements as a traditional one, but the groups will not have the same labels or arrangement as they have had in decades past. DNA studies and phylogenetic systematics have changed the look of the plant kingdom, and our charts need to reflect this. It is hard to find a solid consensus among botanists on the “right” names, but that is no excuse for giving names that we know are obsolete.

I’ve listed my recommendations for contents of a current plant kingdom chart below. The names that I think are most important are in boldface type. The other names may also be useful. Ask yourself, “Will elementary children be able to use this name to find information that they can read and understand?” If you do a search using the name, do you find information that you can use and understand? If not, consider dropping the more technical name and using the common name for the lineage, the one I emphasize below. The terms on charts for children should be useful for understanding the diversity of life AND for finding further information.

Plant Kingdom (land plants, embryophytes)

Bryophytes (nonvascular plants)

                Liverworts (Phylum Marchantiophyta)

                Mosses (Phylum Bryophyta)

 Hornworts (Phylum Anthoceratophyta)

Vascular Plants or Tracheophytes

                Lycophytes or club mosses and relatives (Phylum Lycophyta)

                Euphyllophytes, the “true-leaf” plants

                       Fern clade or Monilophytes (Class Polypodiopsida)

                                  Whisk ferns and relatives

                                   Equisetums or horsetails

                                   Ferns or leptosporangiate ferns or true ferns

                       Seed plants or Spermatophytes

                                    Gymnosperms

                                                   Cycads (Phylum Cycadophyta)

                                                   Ginkgo (Phylum Ginkgophyta)

                                                   Gnetophytes (Phylum Gnetophyta)

       Conifers (Phylum Pinophyta)

                                     Angiosperms or flowering plants (Phylum Magnoliophyta)

                                                                Basal angiosperms

                                                                Magnoliids

                                                                Monocots

                                                                Eudicots

                                                               

For a beginner’s chart, I start the plant kingdom with the land plants, the embryophytes. It is acceptable to add the green algae because they are closely related to embryophytes, but it is clearer if children learn about land plants first, and then add their relatives. Advanced students are ready for a chart of the Viridiplantae (green plants), which includes the green algae lineages and the land plants. It is important for children to understand that land plants and green algae share a common ancestor.

Don’t feel bad about leaving off phylum/division names. While the animal kingdom phyla have been rearranged by DNA studies, they have kept their names. Plant kingdom phyla or divisions, whichever you wish to call them, aren’t as useful anymore. In fact, I have a widely-used, advanced textbook for plant systematics that uses no phylum/division names at all. Instead, it simply uses names with no ranks for the major lineages, such as lycophytes, euphyllophytes, seed plants, and angiosperms. It still uses orders, families, genera, and species, the Linnaean ranks that botanists continue to use for plants.  

There has been a big change that centers on the ferns. An older scheme had four phyla, Psilophyta, Lycophyta, Sphenophyta, and Pterophyta or Pteridophyta. These groups, often called “ferns and fern allies,” were considered more or less equal, but now we know that the lycophytes are a separate lineage from the other three. The fern clade, now considered by some to be a phylum, has three groups once considered separate phyla – the whisk ferns, horsetails, and the true ferns.

I see no reason to put notably out-of-date information on a plant kingdom chart. I especially encourage you to remove any images that are no longer considered plants. If you still have a mushroom on your plant kingdom chart, children are going to associate fungi with plants, even if you tell them that we know now that fungi are closely related to the animal kingdom and not at all close to plants. The visual impression that a chart gives to children is powerful, and it is important to get it as close to current as we can.

Change seems to come slowly in the general knowledge of plant systematics. I did an Internet search for plant kingdom charts and classification, and I found an amazing range of information from very old to current. Some websites even use the terms “cryptogams” and “phanerogams,” which came into use about 1860. Botanists haven’t used them in academic publications for at least 40 years. It is not that they are “wrong,” but they describe a superficial view that botanists had over a century ago. Our knowledge has grown, and there are better ways of expressing the differences among plant groups.

The flowering plants are currently divided into several lineages. I listed the main ones above, basal angiosperms, magnoliids, monocots, and eudicots. Botanists no longer use only the monocot and dicot subgroups, although these are still common in field guides and older publications. The flowering plants make up about 90% of the plant kingdom, and their orders have been defined in the last two or three decades using DNA studies. They deserve their own chart of orders and families.

My plant kingdom chart from my Tree of Life shows the lineages and their relationships. The plant kingdom chart from InPrint for Children gives children more practice with the categories.    

Here are some quick ways to check the information on a plant kingdom chart for your classroom. If the chart shows a row of evenly spaced boxes, it isn’t giving children all the information they need. Bryophytes need to be grouped together and somehow spaced apart from the tracheophytes. Lycophytes should be separated from other spore-producing plants. If the club mosses, whisk ferns, true ferns, and horsetails are all grouped together and perhaps called “fern allies” or “pteridophytes,” that’s obsolete. There should be something to show that the club mosses are a different lineage from the three branches of the fern clade, and if possible, that ferns are more closely related to seed plants. If the term “dicots” or “dicotyledons” appears instead of “eudicots,” then that needs to change. Eudicots (“true dicots”) are the old dicots minus the magnoliids and the basal lineages such as water lilies.

The same criteria for illustrations on a kingdom chart apply to animals and plants. Can you see the important structural features that enable children to recognize the lineage? For example, can you see a fern’s fiddleheads or its sori? Can you see the sporophytes of the bryophyte lineages? Sporophytes need to be visible and described in the text. The reproductive structures and foliage of the gymnosperms help children tell the difference between those lineages. Flower illustrations should clearly show stamens and pistils. Consider showing a fruit as well because fruits are unique to the flowering plants.

In the text for the chart, give children a range of examples whenever this is possible. Children, like much of our society, are less likely to be familiar with plants than they are with animals. They may be surprised to learn that grasses, maples, and oak trees are flowering plants.

Enjoy opening children’s eyes to the diversity of plants! For more information about the plant kingdom and its members, see my book, Kingdoms of Life Connected.


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.  


Tweaking the Tree of Life - Again! August 19 2016, 0 Comments

If you look closely at my Tree of Life chart, you may notice changes. Knowledge about the early branches of the eukaryotes has grown, and it was time for another adjustment in the protists. This time I changed the label on the unikonts to also include a newer term for them, the Amorphea. Some biologists wanted this change because the original hypothesis about what makes the unikonts unique failed. The unikonts do not always have one flagellum, and they have two basal bodies (the part from which flagella grow), like other eukaryotes. What they do have is a unique fusion of three genes. This condition is so rare that it is unlikely to arise twice. The lineage of amoebas, animals, and fungi is still called the unikonts by many biologists, so I left that name on the chart.

The other main branch of eukaryotes, known informally as the bikonts, has a fusion of two different genes, another rare feature. The branch that includes chromalveolates (brown algae, diatoms, ciliates, etc.) and rhizarians (foraminiferans, radiolarians, etc.) has a much less wieldy name. It is now known as SAR (or Sar), an abbreviation for stramenopiles, alveolates, and rhizarians, and I added this to the chart. The evidence now points to some associations that I wanted to include on my Tree of Life. It appears that the Archaeplastida and SAR are more closely related to each other than they are to the Excavata (euglenas, Giardia, etc.). I’ve moved the branch positions on the chart to show this.

I like a newer term for the main branches of the eukaryotes. They are called the eukaryotic supergroups, which is a good descriptor for them.

You may be wondering what to do with your Tree of Life chart if you printed it from the older files. At lower elementary, I would do little more than adding the SAR and Amorphea labels. At that level, it is about showing a broad sweep of life, not the more exacting details. At upper elementary, you may wish to briefly explain about the changes since your chart was printed. Secondary students can learn more about these changes and modify their chart if they are interested.

And then there is that little fact we like to ignore. There are at least as many organisms not shown on our charts (even the more sophisticated scientific ones) as we show there. DNA studies show as many or more bacteria that have never been cultured or named as known bacteria. There are many named, but unplaced protists. Life isn’t simple! Is this the last version of the Tree of Life? Not likely, but it works for now.

You may also be wondering why I bothered to change the chart. Why not start new users of it with the most up-to-date information? As the flood of information continues, it will be best to go forward, not back. The most important thing is that children understand the Tree of Life and the evolutionary history it reflects. As a recent article in Nature Microbiology (2016, article number 16048) states “The tree of life is one of the most important organizing principles in biology.”


Tweaking the Tree of Life December 14 2014, 2 Comments

 

I’ve made a few changes to my Tree of Life and have new files available for free download. The changes are in the prokaryotes and protists. The three true kingdoms, the plants, animals, and fungi are still the same. These changes aren’t large, but they make the chart more accurate and useful.

Perhaps I should start by stating current rules on what constitutes a kingdom. Like any other lineage of life, a kingdom is an ancestor and all of its descendants. Organisms that are not descendants of that ancestor are excluded. That is why the Five Kingdom classification is no longer used. Two of those kingdoms, Monera and Protista, are not valid.

On my prokaryote chart, the only change is in the title. I’ve changed “Kingdom Monera” to “formerly Kingdom Monera” and reduced the font size. I wanted put stronger emphasis on the fact that Kingdom Monera is obsolete. It is no longer accepted by biologists because the two branches, bacteria and archaea, are tremendously different at the cell level. While they may have shared an ancestor very long ago, that ancestor would be the ancestor of all life, not just prokaryotic life.

On my protist chart, I changed both the title and the rhizaria branch. Biologists have good evidence that the rhizaria lineage, the stramenopile lineage, and the alveolate lineage shared a common ancestor more recently than the common ancestor of eukaryotes. The lineage is called SAR, an abbreviation for stramenopile, alveolate, and rhizaria. On the chart, I moved the base of the rhizaria lineage up onto the chromalveolate branch (which symbolizes the common ancestors of stramenopiles and aveolates) rather than showing the rhizaria as equally related to all the bikonts.

There are many uncertainties still in the protists, which are not a kingdom because they exclude the plants, animals and fungi. For convenience biologists group these eukaryotes into the informal group we call protists. There is an overwhelming amount of variety in this hodge-podge of life. When you introduce children to the protists, it is good to tell them that the branches on the chart are just the main branches, the ones with many known members. There are lots of other smaller branches as well. New protists are still being discovered and many that we have known of for years are yet to be studied enough to place them on the Tree of Life.

The Tree of Life gives a good framework for children to use as they address further diversity of life. It’s good to remind them that each of the main branches on the chart holds many other lineages, and life is always surprising us with its endless experiments. No chart will be valid for decades, at least not until we have studied many more organisms and determined configurations of many more lineages.

Happy explorations in life. You can use the comments to ask questions about these changes.

Priscilla


New Product: the Animal Kingdom Chart from InPrint for Children November 07 2014, 0 Comments

Big Picture Science now sells the Animal Kingdom Chart from InPrint for Children. Our stock is the latest printing of this chart, so it has new features. Carolyn Jones Spearman, who is the owner and designer of InPrint for Children, is meticulous in her images and designs. Each time she reprints this chart, she consults me for the latest updates.

With the high rate of change in life science, fueled by new DNA information and Tree-of-Life paradigms, there has been something to change on each printing. On this one, the material is a laminated sheet that lies flat. The color scheme is refined, and there are two new labels placed near the bottom to show the animals that are on the protostome and deuterostome branches of life. These branches are shown on my Tree-of-Life diagram for the animal kingdom.

If you are not familiar with these branches, they are explained in my book, Kingdoms of Life Connected. Briefly, the protostome (“mouth first”) lineage includes mollusks, annelids, arthropods, and roundworms. The deuterostome (“mouth second”) lineage includes echinoderms and chordates. One interesting difference between these two lineages is that identical twins are only possible in the deuterostomes. Their fertilized eggs keep the ability to develop into many tissues through several cell divisions, whereas the protostome cells specialize early. The deuterostome embryos can be divided in half and go on to form two individuals. The protostome embryos die if they are divided in half.

InPrint for Children’s Animal Kingdom Chart includes color cards to place on the chart. Each one illustrates an animal and has information about it on the back. There is a subtle clue to the animal’s environment in the shading behind the animal’s image. If the shading is blue, the animal is aquatic. If it is green, the animal is terrestrial, and if it is pinkish, the animal is a parasite.

This animal kingdom chart provides further experience for children, after they have seen the place of the animal kingdom in the Tree of Life, and after they have an introduction to the major branches of the animal kingdom. Those introductions can be done with my Tree-of-Life charts. The advantage of the chart from InPrint for Children is that it gives children more practice and introduces them to more members of the lineages of animals. The grouping of phyla on the chart reflects the branches on the Tree of Life. For instance, the arthropods and the roundworms, members of the molting animal lineage (edysozoa) are placed side-by-side with a wider margin between them and other branches of animals.

The InPrint for Children chart clarifies the confusion between chordates and vertebrates. Some Montessori materials show non-chordates and chordates rather than invertebrates and vertebrates. Those two groupings are not the same. The tunicates and lancelets are invertebrate chordates. The line on the bottom of the chart shows which animals are vertebrates and which are not.

There is a lot to learn by working with this chart. I hope you and your children find it an inspiring entrance into study of the animals.