Plant Class Lesson Plan #1: Classification

This Spring I ran a little class on plants for one of our co-ops. It was a mixed group of 9 ten year-olds. My motivation for doing this was knowing that my son really needed to cover that plant stuff. I figured I would offer it as my contribution to the co-op and fulfill my obligation while also making sure he got what he needed. 

So far that year in co-op, he had had fun reading and discussing books like The Hobbit and A Single Shard. The kids had also done several weeks of Public Speaking and Debate. It had been a pretty great group and one of the favorite things he did each week. 

Although I enjoyed this group, both moms and kids, I will confess I had a little bit of trouble putting this class together. In the process of feeling the parents out about their views, I learned that at least three of them were creationists... which is something diametrically opposed to science in general and my own philosophy. I had sworn to myself that I would never teach science without evolution, but I now found myself in a position where it looked like I would have to.

To understand why I was so upset by this, you have to understand that much of our knowledge in science of the way the world works is based upon the huge body of evidence that things evolve and change over time. To explain how plants are classified the way they are, it helps to understand how they have changed and adapted over time. Some of the neatest things about plants are the adaptations and partnerships they have formed as a result of weather conditions, soil types, inter-plant warfare, geographic barriers, and plant-insect warfare. 

I almost withdrew my offer to teach at that point, but decided that I shouldn't be obstinate that way. There were still many things I could teach the kids and I ended up dancing around the issue. You should be proud of me. Never once did I say the "e" word to them (though I sorely wanted to). 

I jumped right into that first class with the topic of "Classification". I reasoned that I could discuss with them how plants are classified based upon characteristics. I would have loved to explain that plants started out as simple algae and became progressively more complex over evolutionary time, but I had to keep it to the basic facts. For a kid like me that always had to know the "why", this would have been bad, but they did O.K. with it.

For this course of six classes, I used as my basic source for material and structure an ebook I found on CurrClick called "Understanding Plants and Plant Growth" from the Understanding Science Series by New Learning Publishing. I pulled most everything else from the internet.

On the first day, after getting them to sit down, I pointed out that Botany was the study of plant life.

Then, I asked the most basic of questions. 

What is a plant? I used a white board and they brainstormed some ideas. It came down two or three things.
* First of all, most plants use photosynthesis to make energy from the sun. This is something most animals do not do (although there are some exceptions), nor do Fungi.

* Most plants don't move around like animals do. Again, there are some interesting exceptions, but in general, plants don't move. (Can you tell I love the exceptions?)




* At a cellular level, plants are different from animals in that their cells have cell walls, and things called chloroplasts, where photosynthesis happens. I didn't get too much into the parts of the cell here. I just wanted them to know that this was a major difference. I had a microscope set up with some plant cells on a slide and they were welcome to look at it when we were done, but (sadly) most didn't care that much. 

Next I asked, What do plants need to live? 

Again, after some brainstorming, we came up with this list: sunlight, water, soil (nutrients), carbon dioxide, and space. I took the opportunity at this point to remind them of food webs, and how plants are at the bottom of this. They take their energy from the sun and there are more of them than anything else. The energy they capture filters up the food web to herbivores, and then omnivores and carnivores. 

Now that they were engaged and we had a pretty good handle on what we were talking about, I gave them a hand-out and we dove into the nitty-gritty. I had to promise them that not all of the classes would be like this, but that they really needed to know our classification scheme and where it came from before we did anything else. 

Here is an exerpt from my hand-out.

"In order to make some sense of everything we see around us, we have devised ways of trying to organize the things around us into groups. Carl Linnaeus was a Swedish scientist who lived in the 1700’s and came up with the classification scheme that we use today. He used Latin because it was a language that people still knew but didn't use in every day life. He classified things by characteristics, and we still do, although things get moved around as we learn more about them."

Next we went through the basic order of classification of life. I like this diagram, because it illustrates how the larger grouping encompasses the smaller.
 
For memorization purposes: King Philip Came Over For Grape Soda

We repeated this a few times and then I briefly went over the Kingdoms as most people group them today and what makes the things in one Kingdom different than another.

Getting down the the plant Kingdom (Plantae), I had put together my own diagram for them to look at.

I wish I still had this, because it took me some time to create, but starting at the left with the most simple things, I explained the differences and why we group things this way. First up: algae: red, brown and green - have no veins or complex structures. Mosses and Liverworts are funny things that also have no veins and reproduce by spores. Ferns also reproduce by spores, although they do have veins (are Vascular). On the seed-bearing side, we have Conifers (Gymnosperms), which include cone-bearing things like pine trees, and Flowering Plants (Angiosperms), which are the vast majority of plants that we know. Angiosperms are further broken up into Monocots and Dicots, and the differences between the two are as follows:

Monocots:

Flower parts in                         3’s

Seed leaf (cotyledon)             1

Vascular bundles in stem             scattered

Leaf Veins                                     parallel

Secondary growth                         absent

Dicots:

Flower parts in                         4’s or 5’s

Seed leaf (cotyledon)                        2

Vascular bundles in stem            concentric circles

Leaf Veins                                    reticulate (branching)

Secondary growth                        often present

Some examples might include lilies, which are monocots, versus an apple tree, which is a dicot. Grasses are monocots and tomato plants are dicots. I had some seedlings ready to illustrate the differences in the baby seed-leaves (cotyledons), as well as a samples of mature leaves and flowers from a few monocots and a dicots to look at. They passed these around. I challenged them to find one of each on their own the the next week. I also showed them some classification schemes for a few plants (easily pulled from Wikipedia). For example, celery is in the Kingdom Plantae, an Angisperm, a Dicot (or Eudicot), an Asterid, Order Apiales, Family Apiacaea, and the Species is really the Genus and Species together, Apium graveolens. (To make things more complicated, plants are often put into Divisions rather than Phylums.)

Since the kids had sat so patiently through this avalanche of information, I handed out a fun homework for them to do. You can find it here. They all came back having really enjoyed doing it, especially the part about naming themselves!

After putting their papers away, we did a little growing activity for them to take home. I had ordered some watercress seeds (You can find anything on Amazon!). With some plastic-wrap-covered plates and a padding of cotton batting you can get at any sewing store (pre-cut to fit the plates), we assembled something they could take home to grow. 

I got the idea from a book I had found at the library. Unfortunately, I can't think of the name of it. The idea is simple though. The kids, if they were creative, could have arranged their seeds any way they liked. They could have made a smiley-face or their initials. In practice, it didn't work quite so well, but  after getting the batting saturated with water, they took the wet seeds home and were able to get them to sprout after 7-10 days. Watercress is great because it sprouts quickly, doesn't need much light, and really just needs to be kept very damp. If you wanted to, you could also eat the sprouts. They are supposed to be very nutritious!