Disciplinary Core Ideas: Within cells, special structures are responsible for particular functions; the cell membrane forms the boundary that controls what enters and leaves the cell

Cross Cutting Concepts: Structure and Function; complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the relationship among its parts.

Science Practice: Modeling in 6-8 builds on experiences in k-5 and progresses to developing, using, and revising models to describe, test, and predict more abstract phenomena and design systems.

Lately my goals have centered around my students making real, authentic, and meaningful connections with lessons by using including a variety of models, both from a constructing and evaluating standpoint. Models enable students to describe un-observable mechanisms, like cells and organelles, as well as show relationships among variables, like organelles function and purpose in the cell.

Therefor, by comparing cells to the structures of cities, students would be able to engage in thinking about how organelles in cells work in relation to how municipalities function in cities, something they were most likely already familiar with. By drawing connections to something they were so familiar with, grocery stores, post office, UPS, city officials, I hoped students would deepen their understanding of cell.

Students observed differences in shape, rectangular vs circular , differences in some "specs" in the cell, and differences in the "ring around the cells," thicker on the onion cells. I choose not to do another day of observation of cells but combine this into one day since the observations went fairly quickly, using lettuce leaf cells and prepared slides of blood cells.

Day 2 We started by comparing all four cells, onion, lettuce, blood, and cheek cells in groups then summarized our findings as a class by creating one large Venn Diagram, combining all of the information we observed into Plant Vs Animal (and both) circles.

Students noted big differences in shape, size, movement, specs inside cells, color (although onion and cheek cells were died), and some noted the cell membranes, cell walls, and nuclei.

Day 3 and Day 4 Students researched cell organelles (the specs they noted before in their observations). I gave them a list of websites and resources to gather information from, a list of organelles they would need to describe as well as what information was required for each organelle.

List Included (12): Nucleus, Cytoplasm, Cell Membrane, Cell Wall, Ribosome, Vacuole, Golgi Apparatus, Lysosome, Rough and Smooth Endoplasmic Reticulum, Mitochondria, Chloroplasts

Information Required (4): Location of organelle, shape/color or organelle, Structure (relationship/build) and Function

Students recorded this in packets with spaces provided for each piece of information as well as a diagram of a plant and an animal cell where students added a sketch of the organelle onto a diagram.

Resources I suggested to students:

Enchanted Learning: http://www.enchantedlearning.com/subjects/animals/cell/

Cells Alive: http://www.cellsalive.com/cells/cell_model.htm

Study Jams: http://studyjams.scholastic.com/studyjams/jams/science/animals/animal-cells.htm

Diffen: http://www.diffen.com/difference/Animal_Cell_vs_Plant_Cell

Day 2: Compare all four cells, onion, lettuce, blood, and cheek, in groups then summarize our findings as a class by creating one large Venn Diagram, combining all of the information we observed by Plant Vs Animal (and both). Some students had ideas about cells prior to investigating them with microscopes, but were able to notice something different. For example, students knew cells were the "building blocks" or made up living things, but didn't know what were inside of cells or how the "stuff inside of them" functioned. I assumed students would know onion and lettuce were plant cells which all did, however the cheek and blood cells were more difficult for some to distinguish between plant vs animal. We discussed this based on where they came from in that humans too would count as animals not plants.

Day 3 and Day 4: Students researched cell organelles with the list of websites and resources I provided them with as well as a list of organelles they would need to describe and the information required for each organelle. Students were on task for the start of both days, some students in one of my classes frequently get off task quickly however because of the list of information required, structure, function, location, shape/color, as well as an overall diagram, frequent reminders kept them on pace to finish the required research. Students who did not finish had to do so over the weekend.

Day 5, 6, 7, (8, 9, and 10): Brainstorming, Constructing, and Presenting Models. I went over the research information students were to gather to make sure students began their cell city models with accurate information. Students first brainstormed ideas, what city parts would represent what organelles and why they represented these. This took way longer than expected, some students were unsure about certain city structures and functions therefor delaying the progress of building the models. This extension in time was fine with me because the construction in this model (because of the function), was the most important aspect of the project, explaining why certain features of the city represented certain organelles. Students who finished their brainstorming early, were able to begin constructing their models in class rather than at home (which some students needed to do in order to complete them.) Some students also created a poster or 3-D model then additionally made a power point or Prezi with additional time to be used in their presentations. Presentations were completed on Day 9/10.

Day 10, 11, and 12: Students final requirement for their Cell City Projects was to write an essay detailing summaries of their Cell City and reflections on the unit as whole. went We have been doing a lot with writing and formulating explanations based on observations and models this year because it deepens students understanding of concepts by reflecting and connecting concepts and ideas practiced during units. Some students in the past have struggled with the length requirements of the essay so we decided to have them include certain information as a requirement. We also test our students in this manor through the use of short answer test questions (Compare the cell membrane and the cell wall) and diagramming/modeling prompts (Draw a plant cell, label X organelles).

Day 13: Assessments 3.1 and 3.2 Our grades are calculated via standards based grading and specifically science tests include a range of short answer questions, from which students demonstrated their understanding of concepts learned over the course of the unit(s). Examples include: "Compare the cell membrane and the cell wall." or "Draw a plant cell, label 8 organelles." 89% of students passed (75 total students). Some students confused certain organelles functions with others, lysosomes with ribosomes, mitochondria with chlorophyll, shape of plant cell vs animal cell, but these misconceptions were few and far between. Talking with students allowed me to find out if students really did not know the information, or were confused, nervous, stressed out about the test and would be able to pass a retest. (We do give retest within a two week window at the school I teach at.) I have not gotten into retesting yet, but I assume most students who missed questions on their tests (those with a score of a1 or 2) will retake their tests.

Broad information some students Grasped, some mastered, and some still need more work with, most could complete 1 and 2 and 4, and will need further instruction on 3 which we can hopefully tackle before retesting occurs.

1) Cell shape and function

2) Comparisons between Plant and Animal cells

3) Functions and structures of organelles in plant and animal cells

4) *Modeling can be a useful way to represent understanding of things we can not

Once we all had the information, we were able to start brainstorming and constructing our models! Students selected either a plant or animal cell and designed a city based on the information they gathered on cell organelles functions and structures. First they brainstormed their Cell City via a list which included which city features would represent organelles with brief explanation as to why this city municipality was representative of this organelle. 

For example the Nucleus = the Mayor because the nucleus controls the cell and the Mayor is in charge of the city. Other examples included Mitochondria or Chlorophyll=Restaurants, Vacuoles=Storage Facilities, Cell Membrane=Wall or Fence around cell.

This took more days then expected hence the extra two days. Students constructed a variety of models, some were 3-D, some were posters, some were power points and Prezis. I have students the freedom to choose how they wanted to present their cities. Some organelles like Nuclei, were represented very similarly, but students were surprised to find differences in terms of representation within their cities, but similar functions. (Noting there were a variety of ways to represent the same organelle in different cities.)

Day 10, 11, and 12 Students final requirement for their Cell City Projects was to write an essay detailing summaries of their Cell City and reflections on the unit as whole. 

Requirements for this included: A comparison of plant and animal cells, using information from initial observations, research, and cell city models.

Day 13 Assessments 3.1 and 3.2

We write our own curriculum as well as our own tests. Students were expected to know the basic structure and function of cell organelles, differences between animal and plant cells, and overall cellular function. Test questions include modeling by drawing as well as written response.