#8 Photosynthesis and The Respiratory System

Main Lesson Book
We began, of course, by reviewing the previous lesson, The Endocrine System. Students completed their summaries and illustrations for their main lesson books.

Day One Story & Exploration
In our analogy of The Great River, this system is the Department of Air Quality. But before we talked at all about the parts of the Respiratory System, I gave a presentation on Photosynthesis. My favorite way to do photosynthesis in the classroom is with a large green silk (to represent the leaf) and a box of small square grey pieces of paper labeled O, C, or H with a Sharpie. This box contains enough cards to make one molecule of glucose (C6 H12 O6) by beginning with six molecules of water (H2 O) and six molecules of carbon dioxide (C O2). That means you must prepare six cards that say C, twelve cards that say H, and eighteen cards that say O.

If you really wanted to, you could begin this lesson with a story like All in Just One Cookie. You could even bake a chocolate chip cookie recipe which perfectly matches the ingredients in her story; I like this vintage chocolate chip cookie recipe from BBC Good Food. Why do this? Because you can use the analogy of baking chocolate chip cookies to explain photosynthesis. There are raw materials (the ingredients), a product (the cookies), and a byproduct (the delicious smell).

Begin by laying out the green silk "leaf" and neatly placing the raw materials on it (six molecules of water and six molecules of carbon dioxide). Explain to students that water comes into the plants through the root system and is distributed to each leaf through the stem and veins. Carbon dioxide comes into the plants through little mouths on the bottom of the leaves, called stomata. A plant must have water to live (most children have had first hand experience with this). It also must have sunlight, because sunlight is necessary for a plant to make its food. Again, most children have an understanding that a plant which is stuck in a closet will die, even if it is watered faithfully.

Ask them, "If this leaf of this plant has all of the raw materials necessary to make its food, a sugar, a molecule of glucose... WHY does it need the sunlight? The sunlight isn't needed as an ingredient. Clearly! We obviously have everything chemically to make C6 H12 O6 in the leaf already. It's just sitting there. So what on earth does the sunlight bring to the equation?"

Many children have been taught photosynthesis but don't understand it.

The fact is that the energy from the sunlight rushes in and breaks the bonds between the elements which are currently locked together into molecules. Once these bonds have been broken, they are free to recombine as a molecule of glucose. This is the product. The remaining oxygen pairs up into sets of two (O2) and floats out of the leaf. This is what we breathe in. Plants give off oxygen because it is a byproduct of photosynthesis.

There are several things you can do as a follow-up exploration. Obviously, leave the green silk and box of cards out so that students can try this themselves hands-on. One way is to make another, identical, set of grey squares of felt with Sharpie letters on them, then take the group outside and safety pin a square onto each child who is playing the role of an element. Have them stand on a large green cloth and hold hands to form the molecules of oxygen and carbon dioxide. (Even if you don't have enough to make a full molecule of glucose, you can have three children as water, three children as carbon dioxide, and the remaining children as the sunlight.) The sunlight children rush in and break the bonds. Then the children recombine and the extra oxygens pair up, hold hands, and drift off the fabric "leaf."

You can also do this as a dance. I've had students very successfully go out to the school blacktop with a chime and act out the relationship between photosynthesis and respiration. I wrote it up as a lesson plan on my website.

It's also pretty interesting to recall Geology and discuss how coal is buried sunlight... captured energy from the sun which got locked in the leaves of long-ago fern forests... which then decayed and became compressed layer upon layer upon layer... which then hardened and became a rock... which releases that ancient sun energy as it is burned.

There is also a good story for Photosynthesis in David Mitchell's Wonders of Waldorf Chemistry. There are some facts on page 138 and there's a diagram on page 139, but my favorite is the story "The Great American Forest" by Rutherford Platt on page 140.

If you decide that you want students to do a page in their Human Body MLB on Photosynthesis, I would suggest using the David Mitchell book as your review on Day Two and then have students draft their MLB summary and illustration and add it to their books, before moving on to the parts of the Respiratory System. I didn't have my students include Photosynthesis as a separate page but I spent the time on it because I do think it's really important that they understand the critical relationship between plants and ourselves!

Day Two Story & Exploration
I took my story for The Respiratory System from Linda Allison's book, Blood and Guts: A Working Guide to Your Own Insides.

The chapter is called "Lungs: Airways to the Inside." I required that the older students take notes during the lesson.

We began with page 59 (Pumpers and Separators, Inside the Lung) and page 60 (Locate Your Lungs). We looked at the diagram on page 61 and I passed around the beef trachea which I found at Petco, in the dog treats section. Students were fascinated by the texture and gently felt their own trachea through their skin.

We then read page 61 (Spongy Bellows, Breath Rate) and page 63 (Control). We read the Amazing Facts on page 64. I had my own daughter, who did this block previously, do the experiments on page 65 (In the Bag, Lung Exhaust) but because they are moderately dangerous I didn't do them with a room full of other children. I did describe the experiments in detail to the group. I also talked with them about the origins of the phrase "canary in a coal mine." And we ended by reading an excerpt from chapter 12 of Little House on the Prairie. This chapter is called "Fresh Water to Drink" and it is very dramatic.

Day Three Review & Exploration
On the third day we reviewed The Respiratory System using the nomenclature three-part cards from ETC Montessori. We then built the Model Lung (version 2) using the instructions on page 62 of Blood and Guts. I used an old red wine vinegar bottle, which already had a small hole in it at the top as a pouring spout. It was easy to add the straw and use self-hardening clay to close the remaining space. This model is worth making because the effect of pushing on the diaphragm is quite profound!

We then read page 66 (Air Conditioner in Your Hose, Plain as the Nose on Your Face) and page 67 (Coughs, Hiccups) and talked about how people can cough until they crack a rib because of the way the chest cavity expands and contracts with such force. We also talked about the Heimlich maneuver and how it helps force air out of the body in a way that dislodges something a person is choking on so that it is not fatal. I showed them how to do the Heimlich on themselves with a chair if there is no one else around.

For some of this, I was going into so much detail because I was responding to student questions. One child asked me about victims who have been rescued from nearly drowning. I explained that the body responds to the cold of the water with a reflex that slows down the heart rate and allows the body to use the oxgen that it has in the lungs for as long as possible. There is another good science experiment for this (which, again, has warnings on it so I let Natalie do it several year ago but didn't offer it as an option this time around since I was working with other people's children) in Easy Genius Science Projects with the Human Body: Great Experiments and Ideas. It is Activity 5.2, on page 93, and it is called "Reflexes."

It requires you to hold your breath and plunge your face into a casserole dish or sink full of cold water and ice cubes. Someone takes your pulse beforehand and then while you are in the cold (which stimulates the reflex). *** DO NOT DO THIS EXPERIMENT IF YOU HAVE A HEART CONDITION ***

FYI, I created a document, which is up on my website, with all of the experiments from all three of the human body experiment books we used. It is a chart with the experiment source (book title), experiment name, page number, and complete supply list. I made the chart myself the last time I taught this block and it includes all of the systems of the human body. There are also places on the chart for you to write what day you will do each experiment and what you need to buy or find to be ready for the given experiment. I made it because I personally needed it to keep all the possible experiment ideas straight... or to find out quickly what we could do with what I already had in the house... and I hope you find it helpful! It's FREE.

We did the Nose and Throat Connection Activity on page 67 of Blood and Guts. I also explained to the children about how ducks have their nostrils on top of their bills and have to sleep with their bill tucked under their wing so that they don't drown if it rains. The children found that fascinating!

We read page 68 (Throat Strings, Locate Your Larynx) and I wished I had my dulcimer handy. It would have helped. We also read page 69 (Speech - Lip Juggling) and did the first three activities from Hold Your Tongue. We finished by reading Sinus on page 69 and Cold in Your Nose on page 70.

Main Lesson Book
Students began to draft their summaries and illustrations for The Respiratory System.

Note: This was our final topic for Book I of The Human Body, so students completed their summaries and illustrations, numbered their pages, added their Table of Contents, and did the front and back covers of their book.