Let them eat...Jello?

Cell Structure
One of the Nebraska State Standards is that students will know the form and function of the parts of the cell. I select the 13 that I think are the most important for an animal cell. After we have spent some time discussing the function of each organelle, I try to get them a hands on project to complete so they can remember the functions.

• Nucleus
• Nucleolus
• Vacuoles/vesicles
• Lysosomes
• Cytoskeleton
• Centriole
• Ribosomes
• Rough Endoplasmic Reticulum
• Smooth Endoplasmic Reticulum
• Golgi Apparatus
• Mitochondria
• Cell Membranes
• Cytoplasm

 The final activity we do as a class is to make a model of a cell. I have seen lots of other classes make models of cells using things like paper, a cookie/cake with frosting or clay. However, the aspect of cells that I think students really miss out on is how fluid a cell really is. They see cells under a microscope and everything seems stuck in place and not moving, they see a diagram of a cell and everything is just sitting there and they make a cookie model and everything is just stuck there. However, cells are extremely fluid and everything in the cell is moving all the time. To help show this idea I have my students make a jello cell.(I show this video to get the point across as well).

Here is the outline of the project:

1. Gallon bag = Cell membrane (the bag regulates what comes in and out of the "cell")
2. Cytoplasm = lemon jello (fluid and allows for movement)
3. Plum = Nucleus (The plum has a pit and skin like the nucleolus and nuclear membrane.)
4. Peanut M&Ms = Vesicles (The peanut M&Ms store and transport the peanut)
5. Lysosomes = Gummy bears (bears break things down)
6. Cytoskeleton = Pull and peel licorice (long and stringy like cytoskeleton)
7. Centriole = licorice nibs (a type of licorice because it is a type of cytoskeleton)
8. Ribosomes = chocolate chips (they are small)
9. Rough ER = fruit roll-up with chocolate chips (looks like a folded membrane sack)
10. Smooth ER = fruit roll-up (same as Rough ER minus the ribosomes)
11. Golgi Apparatus = Fruit by the foot (looks similar to fruit roll-up)
12. Mitochondria = Snickers (gives lots of energy)

The students really enjoyed doing this activity because it was a fun way for them to review the functions of all of the organelles.

 To help this be more than just a screw around and have fun day, each group recorded themselves describing each part of the cycle. I was very proud of how well Block 3 did in their description. Block 3 Jello Cell
Here are the rest of the class videos:
Block 2a
Block 2b
Block 1a
Block 1b

This is also a wonderful way for students to study the functions of the organelles without having to sit and stare at a piece of paper. Once again, it is not trying to memorize the functions, but rather remembering how they described them.Of course, the best part of the activity is when the students get to eat them!!

Macromolecules: My Obsession with Paper Models

If a stranger were to walk into my room, the first thing they would notice is all the bright colored paper models hanging around my room. These models were made by my students and, I hope, help them learn some of the basics of macromolecules. The Nebraska state standards say that students should be able to identify carbohydrates, lipids, proteins and nucleic acids. I'm not sure what they mean by identify, but I assume a student should recognize one of these molecules if they see a picture of them, recognize them from a description, and recognize them from their functions. To help students master all three of these skills we have to do more than just give them notes to stare at. Students learn all sorts of different ways, so activities that stimulate more than one of the senses are always good. I do think it is important for students to be able to take good notes because, regardless of how well they learn a concept from notes, if they want to be successful taking college science classes they need to practice taking notes. However, just sitting and writing is ineffective for many high school students. Therefore, each class makes a paper model of each macromolecule.
Carbohydrates
The first complex molecule we discuss is carbohydrates. As they are designing these models, I overhear lots of interesting comments. Students will ask why are they all hexagons and another student will remind them that the monomer is glucose or a student will ask why theirs looks different than another class' model and a student will explain that one each one represents a different carbohydrate. This seems like a great way for students to reflect on what they learned about each macromolecule rather than just stare at a piece of paper. Also, when I review these concepts, I can just walk around the room and point to a model and ask them what it is, how they know that, and what its function is. Instead of them trying to recall what they memorized from their notes, they are recalling the steps they took while building the model and the conversations they had.

Starch

Cellulose

Glycogen

Protein

The next model we made was a protein model. We only talked about proteins in general, but we did discuss primary, secondary, and tertiary structure.We discussed that proteins are a chain of amino acids and then we built that primary structure. Then we discussed secondary structure and the students had to figure out how to give the chain alpha coils and beta sheets (lots of scotch tape!). Then they folded it into the 3-d shape of their choice. Now instead of memorizing what each of these structures are they can just think back to what was the first thing we did, the second thing, and the last thing. I also tweeted pictures of each of the structures so if they couldn't remember, they could just look back at that tweet. Studying tweets of things you did is better than studying a piece of paper.

Tertiary structure of a protein

Lipids

Saturated lipid
Straight chains

Polyunsaturated lipid
Chains with many bends

Monounsaturated lipid
Chains with one bend

Nucleic Acid

ATP/ADP
(with detachable Phosophate)

DNA

RNA

I believe anything that gets students moving, touching, doing and discussing will help them learn more than just sitting and writing. They also really enjoy getting to hang their models anywhere they want in my room and if making and hanging models makes science more enjoyable for sophomores, I am all for it. I posted pictures of these models on my twitter account as they were making them so feel free to check those out as well.

@brandon_timm or #ahsbio