#4 The Eye

Review & Exploration
We began, of course, by reviewing the previous lesson, The Nervous System. For our final nervous system activity, I brought live and cooked bearded mussels into the classroom and we looked carefully at this example of a simple animal. Mussels have no brain and no central nervous system and likely do not feel pain. They DO have a nervous system which is used to detect a predator. If a live mussel is open and you tap it against the counter, you can watch it react and close its shell. The students were fascinated! We also looked at some of the cooked mussels and tried to use diagrams to identify its body parts.

I also had a student use some modeling beeswax to model the brain (inspired by the illustration on page 77 of THE HUMAN BODY: 25 FANTASTIC PROJECTS Illuminate How the Body Works).

Main Lesson Book
Students completed their summaries and illustrations for their main lesson books.

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

The chapter is called "Eyes: Windows on the World." I required that the older students take notes during the lesson.

We began by reading page 87 (Depth). I explained that you can often tell if something is a predator or a prey animal by the location of its eyes. A horse does not need to look down at the grass he is eating. The grass isn't going anywhere. What he needs is to be able to watch for predators while he is eating; therefore, his eyes are on the side of his head. Humans are predators and we need to see in front of us in order to hunt. As the book explains, we have binocular vision... the ability to see in 3-D and have accurate depth perception.

We read page 88 and did the activities (Keep Your Eye on the Ball, Seeing is Believing) and we did the Hole in Your Hand activity on page 89. Students were amazed! Our analogy of The Great River tells us that the Nervous System is the Department of Communication, and that the senses act as Cabinet members and advise the Brain / the President. In fact, the sense of vision is not one advisor, but two. Each eye is a separate advisor and the brain has to combine the two different pieces of information. This analogy seemed to work well! The students loved to play with this, closing one eye and looking at something in the distance, placing the end of their finger over the image, and then leaving the finger in place while closing the open eye and opening the other one. Your finger is no longer covering the object.

Next we read page 90 (Eyes Have It) and talked about the pupil and how much it hurts your eyes when you go suddenly from a dark room into a very bright one, or when you are asleep and then someone turns on your bedroom light. Your window is open very wide when you are in the dark, so that you can get every bit of possible light in to help you see, and when that light comes on... it is WAAAAY too much light and it's actually painful! Then we did activity 3.4 (Are Two Eyes Better Than One When Locating Objects?) from Easy Genius Science Projects with the Human Body: Great Experiments and Ideas. It works best to have a Styrofoam cup prepared for each student in the class. I let my students take home the tube of paper from the Hole in Your Hand activity as well as their Styrofoam cup.

We read page 93 (Camera Eyes, Photo Cells) and I explained that trout can't see in color (which I find very funny, thinking of those fly fishermen who spend a ton of time carefully hand-tying flies to be precisely identical in color and shape to the living things they are imitating). We know that animals can or can't see in color by looking to see if they have rods, cones, or both. Cones are for color. If an animal has only rods, it can only see in black & white.

We did the Shifty-Eyed activity on page 94 and the And in This Corner... activity on page 95. I cut my paper pieces two inches square. You need plenty of clothespins! The colors are red, yellow, blue, black, white, and green. It helps for this activity to buy a scrappack of cardstock which has lots of colors in it.

Day Two Review & Exploration
We reviewed the parts of the eye we learned yesterday and did activity 3.5 (The Blind Spot) from Easy Genius Science Projects with the Human Body. Students were AMAZED!

Next we read page 95 (Eye Color) and page 96 (Eye Defenses, Special Events, Amazing Facts) from Blood and Guts.

Finally, we looked at a transparency of the anatomy of the developing eye in a frog (from the media & supplements sampler to a college textbook Life: The Science of Biology, 7th Edition). We talked about how fragile the eye is (don't run with sticks!!!!) and discussed how so many tasks and professions necessitate eye protection, such as welding helmets.

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

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