End of cell biology unit - beginning of Evolution and Genetics

Last week, on Monday, students presented their cell models (photos posted below). They were all very good! I noticed a few misconceptions during the presentations, so we spent a few minutes reviewing some organelles.

Since we had the field trip to McLaughlin the Friday before, I asked students to write two paragraphs about the field trip. The Knoxville area, where we planted the seedlings, has an interested history so I asked the kids to use this restoration project to illustrate John Muir’s quote: “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.”

On Wednesday, I had three “stations” for them. One was focused on microscopy, and the other two were worksheets – origin of life on Earth and development. I was at the microscope station talking to them about the parts of a microscope, showing them how to prepare a wet mount, and helping them prepare a slide with a piece of elodea, and a slide with their cheek cells (picture below). While one student was with me, the others were working on their two worksheets in their classroom, with Chris. This was the last “official” class covering cells. My goal was to have them think about how the first cell evolved, and to get an initial appreciation of development. This was the last “official” class because on Wednesday we will discuss the worksheets (recall that they are due on Wednesday!).

We have covered all concepts of the 7^th grade standards concerning cells:

Cell Biology

1.      All living organisms are composed of cells, from just one to many trillions, whose details usually are visible only through a microscope. As a basis for understanding this concept:

a.       Students know cells function similarly in all living organisms. b. Students know the characteristics that distinguish plant cells from animal cells, including chloroplasts and cell walls.

c.       Students know the nucleus is the repository for genetic information in plant and animal cells.

d.      Students know that mitochondria liberate energy for the work that cells do and that chloroplasts capture sunlight energy for photosynthesis.

e.       Students know cells divide to increase their numbers through a process of mitosis, which results in two daughter cells with identical sets of chromosomes.

f.          Students know that as multicellular organisms develop, their cells differentiate.

Today we started the evolution/genetics unit. I started by having them tell me what they knew about evolution. They mentioned adaptation, human evolution, and inheritance. We had a good discussion about how these terms are related to evolution, and then I provided a definition, and an example of evolution by natural selection. The example was about the peppered moth during the industrial revolution. We had talked about this example before, and I was surprised to hear how many details they remembered! I then talked to them about Darwin - his voyage, and observations about the finches. I briefly mentioned that Darwin wasn’t the only person working on the idea of evolution by natural selection  (talked about Wallace), and we played a natural selection game at the end of class. The purpose of the game was to illustrate evolution by natural selection at two different levels – predator and prey. Each student had a tool (2 had spoons, 2 had forks, and 2 had plastic tweezers); we walked to a patch of grass by the parking lot where I had previously thrown 100 colored toothpicks (25 of each color - green, yellow, blue and orange), and they had 5 minutes to find, and get toothpicks using their tools. Before leaving the classroom, I asked them to predict the results.  As predicted, colors that could camouflage with the background (yellow toothpicks were blending in with fallen leaves, and green toothpicks are hard to see in the grass) were the most successful at surviving since only 8/50 were found. Orange and blue toothpicks were more easy to spot – 28/50 were found.We spent the last few minutes of class discussing how this game is relevant to evolution by natural selection. 

This is an aggregation of cheek cells. You can see the nucleus in most of the cells.

Cell Biology continuation

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During the first part of science class today, we talked about plant cells. I asked students to think about what structures studied so far (in animal plants) might be found in plant cells. They mentioned cell membrane, nucleus, nucleolus, rough endoplasmic reticulum, and smooth endoplasmic reticulum. I talked about the cell wall, vacuole, chloroplast, mitochondria, and plasmodesmata. We made a drawing of a plant cell with labels and descriptions. I then assigned their cell model homework (due next Monday, November 5^th). We have 3 students working on animal cell models, and 3 working on plant cell models. They will present their models on Monday. I gave them printed instructions for this project (will send parents an electronic version), and they are encouraged to use their drawings from class, and reliable Internet sources (feel free to ask me for references if you don’t know much about the subject) when working on this.

After the break, we talked about DNA – chromosomes, and structure of DNA. My goal was to provide basic, introductory information about transcription and translation so that we could play the “genetic Frankenstein game”. This game can be used for an active, interactive introduction to genes, transcription and translation. Kids are assigned a few physical traits, and asked to build a piece of DNA coding for the assigned traits (codes were provided to students on a handout that is in their science binder that should go home this week). At the end of the game, kids translate the sequences into a Frankenstein drawing. Unfortunately, we were running out of time, and I feel like most concepts weren’t clear. I will spend more time on this activity next week.

A quick note: we will eventually talk about evolution of life on Earth and have a discussion about cells from an evolutionary perspective.

Katrin had enough time to finish a piece of the DNA molecule for the genetic Frankenstein game.

Cell Biology

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This week my focus was on cells. We started by discussing functions of cells, and then started summarizing the structure of an animal cell. I was drawing on the board and having kids draw with me on a paper that will be kept in they science folder (I am not sure if all parents know, but each student has a science folder with all the work that they have been doing). We started with the cell membrane (lipid bilayer with proteins embedded), its functions (protection and regulation) and structure. We also talked about the nucleus; we talked about DNA and RNA (briefly, will talk more about their functions in the near future), the endoplasmic reticulum (rough and smooth), mitochondria, golgi apparatus, lysosome, vesicles, centrioles, and cytoskeleton.

The kids were really interested in the names and functions of the organelles. On Monday, Luke asked about the size of cells (why they can’t be huge), so on Wednesday we talked about diffusion (passive transport of molecules across membrane). We played a game outside – two kids were oxygen molecules, three were the plasma membrane, and two were mitochondria – we then had a discussion about the amount of energy required for diffusion in small vs. large cells. We ended the class with a you tube video (tour of the cell) and I gave the kids the link to a website that summarizes the structures and functions of cells. Next week I will assign a homework project; I will have each student build a model of a cell (plant or animal). They will have one week to work on this, and the link I provided could be helpful for this assignment. I will provide more information about this project next week.

At the very end of class, we talked about the restoration project. We are going to McLaughlin next Friday. Anybody is welcome to join us. We have about 60 seedlings to transplant.

The following standards were covered this week:

7^th grade Life Sciences

Cell Biology

1.      All living organisms are composed of cells, from just one to many trillions, whose details usually are visible only through a microscope. As a basis for understanding this concept:

a.       Students know cells function similarly in all living organisms. b.  Students know the characteristics that distinguish plant cells from animal cells,

including chloroplasts and cell walls.

c.       Students know the nucleus is the repository for genetic information.

d.      Students know that mitochondria liberate energy for the work that cells do.

Next week we will talk about plant cells, and if we have time I will start talking about cell division and differentiation. I will have a summary of the restoration project for kids to read in the car (it will take us a little over 2 hours to get to McLaughlin). 

Below are two pictures of the kids playing the diffusion game:

Becca, Julia, and Katrin were representing the cell membrane.

Garnet was an oxygem molecule looking for mitochondira.

New biology unit

            Last week we only had science class on Wednesday (I wasn't feeling good on Monday). We spent our time finishing the geology unit and checking on our seedlings for the restoration project. The kids had to finish a geology worksheet, finish their geological timeline, and start extra seeds on germination towels. We are going to McLaughlin on Friday, November 2nd, to plant seedlings at the restoration site.
          On Monday we started an unit about life, and cells. This unit will lead us to genetics. I started the class by asking students to discuss, in groups, what it means to be alive. I asked them to create a list of characteristics that can be used to classify things as living or nonliving. Both groups had common characteristics in their lists, including: movement, cells, evolution and energy. I showed them a few pictures and asked them whether they were looking at living or nonliving things. The class wasn't sure about the classification of seeds, fire and coral reef. We then discussed a few more characteristics of living things (respond to stimuli and have metabolism).
          After this discussion, we had our first "lab". I had a small microscope connected to my computer, and we used it to examine our skins, our clothes, sand, leaves, an ant, Vaca's hair and nose etc. We had fun! Chris took some pictures that I will be adding to this post (bottom).
          Today, Wednesday, we concluded our discussion about characteristics of living things and had a brief discussion about genes and evolution. It was a very interesting discussion - the kids were really involved and actively discussing their thoughts. One of the students asked me why some plants have thorns and I asked them why thorns would be an advantage for the plant. Katrin and Rodrigo talked about protection (of genes), and Garnet was really interested in knowing why/how new traits establish. I told them that mutations are random events, Luke pointed out survival of the fittest and we talked about adaptation.
          On Monday, a few students weren't convinced that seeds are living things so we dissected a bean today. I showed them the embryonic leaves and root. During the last few minutes of class, students looked, under a microscope, at single celled organisms that live in Putah creek.We saw algae and rotifers. Next week we will take a look at cheek cells, plant cells, and some more protists.

Yosemite's Biotic Zones project

 In the last two weeks, students have been learning about the 5 biotic zones found in Yosemite. They spent the first day summarizing their assigned zones and had two sessions to work on the models.

Becca and Garnet worked on the foothill-woodland zone and the lower montane forest. Josh, Luke, and Rodrigo worked on the upper montane forest and on the subalpine forest. Julia and Katrin were responsible for the alpine zone and fire ecology.

Yesterday, Wednesday Oct. 3, students presented their projects to the lower grades.

Here are some pictures of the final projects: 

Geology Friday - Pictures

Here are some pictures of last week's geology Friday session:

Julia, 7th grader, demonstrates how a glacier moves while 3rd-4th graders observe.

3rd-4th graders take a closer look at how glaciers shape landscapes.

5-7th graders present the plate tectonics poster.

Rodrigo presents the plate tectonics poster to 3rd-4th graders.

Teacher Pa helps 3rd-4th graders with the rock cycle activity.

Making mold fossils.

Week 3 - end of the geology unit

This was a science intense week! The upper grades had geology class on Monday, Tuesday and Wednesday, and on Friday they helped teacher David and I teach the material that they have learned in the past two weeks to the lower grades.

On Monday we reviewed the plate tectonics worksheet, and talked about the rock cycle. We did an activity using crayons to illustrate the rock cycle. Students were separated in three groups, each group had 3 crayons of one specific color. The crayons represent different types of rock. Students were told to shave the crayons, and I asked them what part of the rock cycle this action was representing. It was clear that all students knew that the shaving was representing erosion. The next step was to place the crayons' shavings on a piece of aluminum foil - one color at a time, and one layer on top of the other. This resulted in the formation of a sedimentary rock. After all students had a chance to take a look at our model of sedimentary rocks, I closed the aluminum foil, and asked each student to apply pressure to the package. Metamorphic rocks are created when other types of rocks are exposed to heat and pressure. After examining our crayon metamorphic rock, we went to the kitchen and placed our foil in boiling water for about 10 minutes. The melted crayons were allowed to dry until the next day. The boiling part of this project simulates the formation of igneous rocks.

On Tuesday we took a look at the cooled igneous rock, and then we tried a slightly different approach to make fossils (mold and cast) with clay and plaster. I brought small paper cups to the classroom, and asked the kids to make smooth balls of clay to place inside the cups. They placed the clay inside the cup, flattened the top, and applied a small amount of Vaseline on the surface. Each student chose a small plastic animal, and pushed it on the surface of the clay to make a mold. When they were done with their molds, I poured platser in the cup until it was almost filled and the plaster was left to dry. After this project, students were divided into two groups (one group was responsible for preparing posters and presentations for the first and second graders, and the other group was responsible for preparing posters and presentations for the third and fourth graders).

On Wednesday we checked on the fossils and were happy to find out that we were successful with our second approach.  I presented a mini lecture on glaciers that covered the following topics:
- What are glaciers? How are they formed and how do they move?
- How can glaciers shape landscapes? My focus was on plucking, abrasion, and moraine formation.
Students seemed to be very interested in this subject! Most of them didn't know much about glaciers, and they showed a lot of interest in the topic. After my presentation, the two groups prepared a glacier to be used in Friday's geology session, and they had approximately 45 minutes to work on their posters and practice the presentations.

On Friday we had a geology session for the whole school in the morning. There were four half-hour activities. Teacher David helped the older kids work with the first and second graders, and I helped those that were working with the third and fourth graders. You can find a summary of what we did on David's blog (http://grainworldsand.blogspot.com/). I was really happy to see, and hear from David, how the upper graders were knowledgeable about the geological concepts being covered. The students who were working with me in Brittany's class did an EXCELLENT job answering questions and presenting their posters. Unfortunately, we didn't have much time to talk to the 5-7th graders about how to present the information and introduce the activities, so David and I ended up doing most of the talking.