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.”
Smile! It makes you feel good, and it helps others to do the same. I found some interesting ideas about how did our ability to have facial expressions arose as I researched mammals lately. It all started long ago with the first synapsids, the lineage that led to mammals. Although Dimetrodon is a synapsid on a different branch of life than mammals, that animal has a piece of the puzzle on smiles.
“Dimetrodon” means “two measure teeth” or “two long teeth.” Compared to its reptilian sister lineage, the synapsids were experimenting with different shapes, sizes, and therefore, functions of teeth. The reptiles, even the dinosaurs, have more uniform teeth. This shows two different strategies for eating and digestion. Synapsids developed the ability to chew their food. Reptiles, with only a few exceptions, are bulk feeders, meaning that they eat large pieces of food (like a snake eating a rat) and digest them slowly or they use a muscular stomach to grind the food (like birds and other dinosaurs).
The study of mammal evolution focuses a great deal on the study of teeth. Not only do teeth fossilize well, they show the changes as mammals arose and lineages developed. A key characteristic of mammals is teeth that can do a better job of biting, chewing, and grinding.
What’s the big deal about chewing our food? It has to do with how fast the food can be broken down by digestive enzymes. All the action of enzymes is at the surface of the food. Lots of surface area equals fast digestion. And why would one want to digest food quickly? Quick digestion leads to quick metabolism and production of molecules that supply energy to cells. It is necessary if the animal is warm-blooded and has a large brain. Maintaining our body temperature and feeding our brains are very expensive in calories.
OK, we chew our food and digest it quickly, maintain our warm body temperature, and feed our expensive brains. What does that have to do with smiling? In order to chew food, an animal needs muscles that operate the jaw. That seems straight forward enough. Those muscles must attach to the head, and an array of muscles around the head brings another possibility – the ability to have facial expressions.
Have you ever seen a facial expression on a fish, amphibian, reptile, or any of the avian dinosaurs, aka birds? They don’t chew their food, and they have few, if any, facial expressions.
Most mammals, on the other hand, have many facial expressions. Evolution is not a straight line, climb-the-ladder sort of thing, so some mammals have lost the ability to have facial expressions. Or perhaps their expressions are so subtle that we can’t see them. I’m thinking of whales and dolphins. Their use of sound to communicate probably works better than small visual changes because of their aquatic environment.
The social mammals that live on land have many ways to communicate. Many mammals use the position of their ears to express themselves. A snarl shows teeth and speaks loudly across many mammal lineages. Facial expressions are important and versatile ways of communicating for the more visual lineages, like primates. Our smiles likely started millions of years ago, judging by the use of facial expressions in our fellow great apes.
I recommend a generous bestowing of smiles on your fellow humans. You can celebrate that your ancestors took the road to chewing food as you smile. It is a fine thing to celebrate the wonder of our long journey as a species as well.
The first time I introduced children to the chemical elements, I wanted to give them a sense of where they might find these substances, either as single elements or in combination with others. Laying out the periodic table is one experience with the elements, but it is quite abstract and disconnected with everyday life. I wanted to help children learn about the elements in common substances, items they could encounter and experience.
I made a set of cards that had pictures of items, and I listed the major elements in each one on the back of the card. To let you know how long ago that was, I printed the lists of elements with a dot matrix printer and an Apple II computer. Fast forward a decade or so, and Carolyn Jones of InPrint for Children was designing a new series of materials for study of matter and atoms in Montessori elementary classrooms. We discussed the idea of a card set that shows common objects and their elements. She took the idea and produced an attractive set of cards that she calls “Elements Around Us.” Presently, only Big Picture Science sells this set.
“Elements Around Us” has photos of 20 objects. The set includes two copies of each card, one to leave whole with text that tells the elements, and one to cut apart for matching. We intentionally used some substances to simulate thinking. The photo of a cotton towel (which is mainly cellulose) and table sugar both say “This is composed of carbon, oxygen, and hydrogen.” Cellulose is a macromolecule that is built of sugar molecules. These cards lead to the concept that elements can be joined in many ways to make different substances. The card that shows gold colored coins lists no gold as an ingredient. There are cards for carbon in the form of graphite and of diamond.
After children have worked with the cards, they are often interested in doing more. The “Elements Around Us” set has a black line master called a replicard, which you can copy for children so they can make their own booklets. They can color the outline drawing and write the elements. There are two blanks for children to draw their own object and research its elements.
Elementary children who are past the stage for card materials or who want to pursue the idea further will likely enjoy How to Make a Universe with 92 Ingredients, a book by Adrian Dingle. The book, Planet in a Pebble, by Jan Zalasiewicz, begins with a chapter on the elements in a common beach pebble. This book is for adult general readers, but selections from it can be read to older children or read by secondary students.
Happy element hunting!
World Read Aloud Day, February 24th, slid by me while I wasn’t looking, but I hope you celebrate reading aloud every day. I learned about the “official” holiday from Science Books and Films (SB&F) February issue, which included this book list.
10 STEM Books for Reading Aloud
A Chicken Followed Me Home, by Robin Page. Simon & Schuster, 2015.
You Nest Here With Me, by Jane Yolen and Heidi Stemple. (Illus. by Melissa Sweet.) Boyds Mills Press, 2015.
Tiny Creatures: The World of Microbes, by Nicola Davies. (Illus by Emily Sutton.) Candlewick Press, 2014.
Raindrops Roll, by April Pulley Sayre. Beach Lane Books, 2015.
Winter Bees and Other Poems of the Cold, by Joyce Sidman. (Illus. by Rick Allen.) HMH Books for Young Readers, 2014.
One Plastic Bag: Isatou Ceesay and the Recycling Women of the Gambia, by Miranda Paul. (Illus. by Elizabeth Zunon.) Millbrook, 2015.
Tree of Wonder, by Kate Messner. (Illus. by Simona Mulazzani.) Chronicle Books, 2015.
High Tide for Horseshoe Crabs, by Lisa Kahn Schnell. (Illus. by Alan Marks.) Charlesbridge, 2015.
Waiting for Ice, by Sandra Markle (Illus. by Alan Marks.) Charlesbridge, 2012.
Feathers: Not Just for Flying, by Melissa Stewart. (Illus. by Sandra S. Brannan.) Charlesbridge, 2014.
I reviewed Tiny Creatures in a post for September 2014. Feathers: Not Just for Flying is a favorite of mine, both for the beautiful artwork and the science content.
If you subscribe to SB&F, you will receive the full content, which includes special features like this month’s list of books about technology and innovation for Black History Month. There is also a Read-Around-A-Theme feature on bats, and the usual great reviews of books for kindergarten through adult general readers.
If you can’t subscribe now, you can still get several valuable resources on the SB&F website (http://www.sbfonline.com/Pages/welcomesplash.aspx). This month there is a list of children’s books to celebrate spring, biographies of women in science, and science poetry for kids.
I have two new posters that do a good job showing the history and diversity of life. The first is just out from Fairhope Graphics, and it is called “A History of Existing Angiosperms.” The many branches of flowering plants show up very well on this poster. You can see why there’s more to flowering plant lineages than monocots and dicots. The timescale on the left of this poster could lead to confusion, so you will need to explain to your children that all the pictures show flowering plants that still exist. Each illustration is placed at the time when we think its lineage originated.
An important qualifier for this information – plant fossils are so much harder to find than large vertebrate fossils. Paleobotanists have to piece the story together from small, hard-to-preserve fragments, not large bones, so it could well be that a number of these plants will have a different age of origin as scientists obtain more fossil data. That should not detract from the information show here, however.
You can see from this poster that the plants had developed their major lineages before the K-Pg (K-T) extinction, and these lineages survived much better than the large vertebrates. The poster has the number of species and the common names of a few members for each lineage.
Look for the three main branches of angiosperms, the magnoliids, the monocots, and the eudicots, on the poster. You can also find two large branches of the eudicots, the rosids and the asterids. The rosids split into the fabids and the malvids. The asterid subdivisions are the lamiids and campanulids. These seem like a bunch of big meaningless names until you put a flower image with them, so this Fairhope Graphics poster will help make the lineages more memorable.
Fairhope Graphics also has useful posters on the lineages of birds, the Tree of Life at a simple and more advanced level, and the history of the Earth.
My second recently acquired poster is from a company called Evogeneao, which they explain on their website is short for evolutionary genealogy. The motto of this organization is “Life on Earth is one big extended family.” Their “Evolution Cousin” poster shows their branching diagram for all of life, along with several familiar organisms and a number that reflects their relationship to us. For instance, your cat is your 27 millionth cousin. You can also get a larger poster that features the Tree of Life as the main graphic and gives information about it. These posters would be great for an impressionistic lesson on the Tree of Life. If you decide to use one of these posters in your classroom (or even if you do not) you will find it useful to read the Tree of Life page under the “Learn” menu on the Evogeneao website.
Under the “Explore” menu there, you can select “Tree of Life Explorer.” When you can click on an organism, you will see lines appear from humans and the selected organism. These lines meet at the most recent common ancestor. It is a very cool illustration of our relation to all of life.
With summer nearing the end and fall coming fast, do your thoughts turn to leaves? If so, I’ve got a new card set for you -- Leaf Shapes and Margins. I’ve been collecting photos of leaves for many years. I selected 44 species that show a variety of characteristics and turned the images into cards for the classroom. Each card has a single leaf, sans background, along with its common and scientific name. Here's the card for the aspen leaf. It is half a letter-sized page (5.5 X 8.5 inches) in real life. You can see the details of its venation and the structure of its margin.
While I designed this set for older elementary children to use in leaf shape studies, it can be used by any age for appreciation of the beauty and variety of leaves. It takes math and botany to describe leaf shapes according to the Manual of Leaf Architecture by Beth Ellis, et. al., a highly respected professional botany reference. First one must measure the length of the leaf blade, and then divide it into five equal parts. Next one must find the widest part of the leaf blade and see if it falls within the middle fifth, in the basal two-fifths, or in the two-fifths nearest the apex. That determines elliptic, ovate, and obovate shapes respectively. An oblong leaf has about the same width through the middle one-third of the leaf blade. A linear leaf is at least ten times longer than it is wide. Those are the five major leaf shapes. This more precise system of determining leaf shapes replaces an overwhelming number of loosely defined traditional terms.
Warning – to prevent brain strain, do NOT measure in inches. Use centimeters, and you will appreciate why scientists (and most of the world) use the metric system.
For more math and botany, one can measure the angle of the apex and base of a leaf and decide if these angles are acute, obtuse, or reflex. For the base, there is one more situation, a circular base. The shape of the apex and base are also part of the leaf description. There’s more about this in my book, Plant Lessons: Introducing Children to Plant Form and Function.
Margins can have teeth, lobes, both structures, or neither. There are leaves that show all these situations in the set. The leaves include common trees, such as oaks, maple, and elm, as well as houseplants and weeds. Crabgrass comes in handy when you need a linear leaf. No one minds if you pull it up. The bo tree shows how a drip tip looks, not something you will find in your neighborhood unless you live in a tropical area.
The background information that comes with this new set includes a few sentences about each of the plants whose leaves are shown, a procedure for determining leaf shapes, and a table that gives the description of the leaves so you can check your results.
More than anything, I hope this card set inspires all ages to look more closely at leaves and appreciate the wonderful structures of these food factories for life on Earth.
Happy Fall Botany!
Summer is a great time to play, and I still enjoy playing with my science observations. Light and color are great subjects for exploration. Put it all together and here’s what I’ve been doing.
First of all I ordered a bag of UV beads from Loose in the Lab, a company in Salt Lake City, UT. These beads are available from a number of suppliers on the Internet. They are plain white beads in artificial lighting, but when they are outdoors in sunlight, they turn bright colors. A substance that reacts to something we can’t see and allow us to see it is often called an indicator, and these beads are an indicator of light that has too short a wavelength for us to see.
I noticed one day that these UV beads developed pale colors on the window sill, where the glass should have filtered out any ultraviolet light. Either the window glass was letting in a some UV or the beads were coloring from the shortest of visible wavelengths.
I checked the ability of shorter wavelength visible light to color the beads using a window sill prism that projects a nice spectrum of light across the room. I placed the bag of UV beads in the “rainbow” and saw that the beads in the violet light at the top of the spectrum caused some of the beads to color. The beads that turned blue and purple in sunlight also colored lightly in violet light. None of the beads in red, yellow, green, or blue light changed color.
I also researched window glass transmission of UV light on the Internet. I thought that glass blocked UV, and I found that it does block UVB, the wavelengths that cause sunburn and allow us to make vitamin D in our skin. I was surprised to learn that glass transmits appreciable quantities of UVA, the longer UV wavelengths that age skin and can cause cataracts. It is unlikely that any seating in your classrooms put children in direct sunlight in the middle part of the day because of the heat, but if so, you may want to move them to avoid UVA. Morning and afternoon sun is less intense, so sunlight at that time is not such a hazard.
The beads that colored in the violet part of the spectrum tell me that the shortest wavelengths of visible light will cause color change, and I suspect that the UVA coming through the window is strong enough to change them as well because the colors were stronger on a sunny window sill than in the violet light. The sunlight coming through an acrylic skylight colors the beads quickly, but not as deeply as direct sunlight, so I suspect that the skylight cover transmits a lot of UVA. In case you are wondering, polycarbonate plastic, which is often used in safety glasses, blocks all UV light. Children should have these safety glasses if they use UV or “black” light. Their eyes are specially sensitive to UV damage.
What can children learn out of this experiment? Different wavelengths of light are different colors, and the shorter wavelengths (violet) carry more energy than the longer wavelengths (red). There are wavelengths of light that we can’t see, but other substances allow us to detect them.
Children can address many questions using these beads. They may be interested in the ability of clothing or other items to block UV light. Does UV light come through the clouds? Have fun finding out!
I’m continuing on my commentary about my botany materials and how to choose them, this time with emphasis on the older elementary child.
Children in the 9-12 year-old range have different needs than the younger elementary ones, so they are not likely to find the little booklets and three-part cards of Illustrated Botany for Children attractive. They can, however, use the wall charts (summary charts) from that material to review or to check on terminology. The file for printing the wall charts by themselves is available. See http://big-picture-science.myshopify.com/collections/montessori-botany-materials/products/illustrated-botany-for-children-wall-charts-only
If you have my book, Plant Lessons: Introducing Children to Plant Form and Function, you have a number of lesson avenues to further botany studies. If your children have had the basics, then you can go deeper into flower structure, plant adaptations, fruits, and seed structure and function.
My botany photo cards set 1, Major Branches of the Plant Kingdom, is a good way to launch studies of the diversity of plants. While I would hope that you can have many of the branches of the plant kingdom represented in classroom houseplants, you are not likely to have many reproductive structures or the rarer plants available. The photos allow children to see structures and plants that you can’t otherwise provide.
If you are basing your botany studies on flowering plant families (an excellent way to structure botany), then you have lots of interesting botany yet to cover. Even if children studied a flowering plant family each month in their three earlier years of elementary, that is only 27 families out of over a hundred that might be found in temperate North America, either as natives or imported ornamentals or as food plants. The total count of angiosperm families is 413 in the last official publication. The number of families that you may experience will depend on the continent on which you reside, and on your local climate and growing conditions. The tropics have a much greater diversity than temperate areas. If children have not studied flowering plant families before, they can dig into them at upper elementary level.
Photo card set 2, Flowering Plant Families, is an introduction to 14 flowering plant families. The photos each have text on the back to start children’s research about these lineages. The families are a sampling across the major lineages of angiosperms. The efile of my PowerPoint presentation on flowering plant families, designed first for adult botany education, is available as a download. This pdf shows 20 families, eleven of which are not in photo card set 2. The PowerPoint slides are illustrated with color photos, and the pdf is at sufficient resolution for printing. Purchasers have the right to print the slides, but only for their own classroom. The slides can serve as research starters, although the photo cards have more information, and the text is in complete sentences vs. the phrases on the slides.
Photo card set 3, 48 Flowers for Study and Sorting, can be used with many levels of students. This set has examples of a wide variety of flower features, and includes a table to help teachers pick the right cards for a variety of lessons, from simple naming of flowers to details of their structure. While younger children will likely be sorting the pictures, upper elementary and secondary students can use the accompanying text cards to learn more about the structural details and the lineages of the plants. For example, the photo that symbolizes this set is a flower of blue flax. It is a eudicot flower with distinct petals that shows radial symmetry. The text card tells that this plant is a member of the rosid lineage of eudicots, and of the fabid lineage of rosids. Its order and family are also given.
How about structuring your botany around food plants? You could combine history of the plant’s domestication, botany of its flowers, and even include to culinary uses. The practical application of farming at middle school level is another layer of this study. Knowledge of flowering plant families can help with the planning of crop rotation and fertilizer applications.
Dig in! Enjoy the unfolding miracles of the plant kingdom that go on all around you.
I’m going to go off on a tangent before I discuss materials for botany studies with older elementary children. I’ve been researching an important tool for botany studies, a hand lens.
A hand lens (aka pocket magnifier) is very useful for botany studies. Many flowers have parts too small to see without magnification, and there are even whole flowers that are too small to see without this help. Regular magnifying glasses are usually 2-3X magnification, but what you need for botany is something in the 4X to 5X range. With that you can see the texture of stigmas and even the larger pollen grains on anthers.
In years past I have been able to purchase 5X glass hand lenses. The lens folded into a plastic case that protected it while it was being carried outdoors. When I tried to find more of these lenses, I found they were no longer available. I searched the Internet, especially Amazon, looking for a replacement and ordered several to try. Here’s what I found.
The only hand lens that had the magnification described on Amazon was the Bausch and Lomb 4X folded pocket magnifier, which cost about $14. I’m now carrying that one in my pocket as my personal lens, but that is a bit pricey for a classroom set. I found that the inexpensive lenses on Amazon were not as advertised. One that was listed as a 4X was actually a 2X. One with glass lenses came with a large scratch on the lens, and its magnification was half of the description. A “bug loupe” that was labeled 5X is actually closer to 3X, and it focuses only when held above the surface, not when resting on its clear plastic housing, which one presumes was there to contain the bug. My basic message: Let the buyer beware when it comes to inexpensive hand lenses.
To tell the magnification of a simple lens, first measure its focal length. You can do this by focusing an image of a light fixture or the scene outside a window onto plain paper. Then you measure the distance between the paper and the center of the lens. If you measured in inches, divide that measurement into 10. If you measured in centimeters, divide that measurement into 25. The result is the magnification. This means that a 5X lens should focus about 2 inches or 5 cm from the paper. A 4X lens should focus at 2.5 inches, and so on.
In the end, I decided that I will have to settle for plastic lenses, although they will scratch easier than glass. Acorn Naturalists has a small 5X lens for about $4, so you can get several for botany or other work. The lens is about an inch in diameter, which is easier for children to use than the narrower 10X lenses. Ten times is more magnification than one really needs, and the short focal length means that you cut off the light as you bend close to look.
With all these lenses, you need to hold the lens close to your eye and either bend down or bring the object up until it is in focus.
I hope this information helps you find the lenses you need for botany and other outdoor observations. If you have found a better alternative, please let me know.
I’ve heard from teachers that they are not sure what to buy or how my materials fit into their lesson sequence. Here is some information that I hope helps you with those decisions for your botany studies, as well as a link to our complete range of Montessori botany materials.
Plant Lessons: Introducing Children to Plant Form and Function. This book is the anchor for your botany studies. It gives you the lessons you need to present children with the parts of plants and what those parts do. It starts with basic lessons and continues through elementary, at least. At middle school level, it is helpful for review and to fill in gaps in plant knowledge that children may have.
For early childhood – Basics lessons on the parts of a plant, kinds of roots, and the parts of a stem, leaf, flower, fruit, and seed. Other lessons on the whole plant – deciduous and evergreen, plant life cycles, growth forms, and basic reproduction (whether the plant makes spores or seeds, or reproduces vegetatively). The five basic leaf shapes, and other leaf lessons as needed.
For first level elementary (6-9 year-olds) – All the lessons are appropriate, although it is highly unlikely that all be needed in the first three years of elementary. If children have not had the basic lessons listed under early childhood, they should receive those first. Past basic lessons, the lessons can be guided by the available plant materials. Lessons such as “Woody Stems in Winter” are best when the real plant material is available. Flower lessons can be matched to the flowers that are available. It is more important to use the lessons to further children’s knowledge of real plants than to march through all the nomenclature. If you follow the development of plants on your school grounds and in the area through the year, and supplement with cut flowers, you are likely to give your children an excellent foundation in botany.
Illustrated Botany for Children is the botany nomenclature booklets and three-part cards for the children’s work in botany. The language level is simple enough that the young reader can manage it with a bit of help. There is a nomenclature booklet and accompanying cards for each of the lessons in the Plant Lessons book. The wall charts (summary charts) give a visual overview of each lesson and help children remember and review the content.
48 Flower Cards for Study and Sorting (Botany photo card set 3) is useful both to use in flower lessons and in follow-up work for the children. The table that comes with the cards tells which cards are useful for a wide range of flower lessons. For example, children can sort cards that show tepals vs. petals and sepals, or they can use the cards to practice finding stamens or pistils.
The Story of Poinsettias and The Amaryllis are children’s books for beginning elementary. These are available as files that you print. They are illustrated with color photos that show the botanical details. When these flowers are in season, the books are a great way to help children see the flowers’ important details. These books also work as a read-aloud for younger children.
Early Spring Flowers is another file that you print to make study and research starter cards. It helps children learn the names of flowers and see those challenging inconspicuous flowers on trees like maples and alders. Older children can learn more about the flowering plant family and other plant classification.
Plants We Eat is a set of six booklets and matching cards for kindergarten and beginning elementary. This material from InPrint for Children is a great way to make lessons on the parts of a plant more meaningful. The set includes a master for copying booklet for the children to color and label.
Leaf Characteristics is another set from InPrint for Children that is very useful for kindergarten and beginning elementary. It helps children learn to observe the pertinent features for leaf description and is a good foundation for more advanced leaf studies.
I'll continue with recommendations for older elementary children and middle school level another day (but you can always email me with your questions). Today I feel the need to get my hands in the soil and observe my own garden plants.
Priscilla