Planning a 7th Grade Lesson on Cells

© 2010 Victoria Deneroff PhD. May be used by K-12 educators, but not republished in any form.

This is part of an unfinished essay I wrote in response to a student teacher’s question, “Well how would you teach about cells?”

The context of the conversation is a curriculum class. Teacher candidates were debriefing their experiences during field placement. One of them described to me his host teacher’s lesson on parts of the cell. What he described was a vocabulary lesson. Since I had observed a different host teacher on the same topic a few days previously, the teachers having co-planned, I had a pretty good idea what had occurred. I waited for the student teacher to critique the lesson. I asked how he thought the lesson was structured. “Fine,” he said. I purposely brought forth a little emotion. “That was a horrible lesson,” I said. “What you described is not the learning of science, but a vocabulary lesson.” He responded that he didn’t know any other way to teach about parts of a cell, and asked, “Well how would you teach about cells?”

What follows is a description of how I would start teaching about cells in a manner consistent with best practices in teaching science.

Before starting, I always spend time considering what I, as an expert, know about the topic. My goal in this essay is to make my thinking available to students (that is, student teachers).

  1. Start with my principles. ALWAYS. It might seem like a lot of work, but with practice, it becomes second nature. If you are going to take short cuts, show a video or pass out worksheets, but never plan without reviewing your principles.
    1. Learning cycle

i. Brain structure determines what experiences students need in order to create meaning.

ii. All learning must start with concrete experience.

iii. Learning must be connected with experience and connections between new knowledge and old is the first concern.

iv. New knowledge will be retained if it is connected in a way that makes sense.

    1. Social constructivism – Vygotsky & Tharp & Gallimore (you read Tharp’s article this week)

i. All higher order learning (such as happens in school, what Vygotsky calls “scientific”) is mediated through language.

ii. The more students speak about the learning task, the more they will learn.

iii. One of the goals of instruction is to take students’ disparate prior knowledge and turn it into the group’s common knowledge.

iv. If students could do the tasks completely on their own, they are not in the zone of proximal development and don’t need a teacher. On the other hand, if they cannot do the tasks with help, it is beyond their competence and instruction is useless.

v. Forcing students to publicly display incompetence prevents their full participation in classroom processes.

vi. Students are constantly using the public space to assess their own and others’ competence.

vii. Young adolescents are particularly concerned with learning about their place in the social world, which means that social learning is developmentally appropriate.

    1. Inquiry

i. Science is the process of asking questions and finding explanations in a disciplined and structured way. This is the generation of new knowledge.

ii. “Known facts” of science are answers to previous questions.

iii. Providing students with opportunities to think like scientists is the goal of science instruction.

iv. All instruction is about the generation of new knowledge—even if it is “old” to science, it is new to students.

  1. Distill these principles into pedagogical heuristics. (Heuristics in this case means rules of thumb, a framework for all instruction, something to fall back on as a check of whether I am on track.)
    1. Learning cycle

i. I have to make sure I am going to allow students many opportunities to experience all 4 stages.

ii. I want to start with children interacting with materials and phenomena. In other words, I must have something concrete, hopefully as close to the real thing as possible, to start off with.

iii. I must spend much time helping students investigate their prior knowledge. It is not always obvious to students what they already know. Ideally, the boundary between old and new knowledge will be invisible to students. That is, the investigation of prior knowledge will slip over into generation of new knowledge seamlessly.

iv. I will focus continuously on making sense, on the big concepts, on tying details back to the overarching big ideas.

    1. Social constructivism

i. The environment will be “language rich” with talk, reading and writing.

ii. It doesn’t matter how much I explain things, what matters is that children can explain them. I want to arrange instruction so children must make explanations to each other as much of the time as possible. The goal is 80% student talk, 20% teacher talk.

iii. In order to have the group develop common knowledge, we must get important ideas onto the public floor.

iv. It is impossible to tailor instruction to every child’s ZPD. I must choose and design activities that have multiple entry points so all children can find a ZPD. The small group can scaffold when I can’t get to every child. This does not mean the brighter children teach the less bright. It means there are conversations in which every student can participate and learn.

v. Children need to have control over their participation so that they do not have to embarrass themselves. I need to create an atmosphere of safety.

vi. Children are going to make judgments about their own and others’ competence and I may need to intervene so that everyone has an opportunity to publicly display competence.

vii. Cooperation, team-building and social skills are part of science as well as young adolescents’ developmental needs.

    1. Inquiry

i. I will position myself as an inquirer and not an authority figure who knows the answers.

ii. I will engage students with the history of science so they can see where science comes from.

iii. I will not answer many of students’ questions, but think with them about how to find out.

iv. I will provide a framework of big ideas so that students can generate knowledge of their own.

  1. Concepts. I have to think about the big science ideas. There is no shortcut to doing this, and it takes time. It might mean reading, or watching an Annenberg video.
    1. Big ideas about cells

i. Living organisms obtain energy from their environment, remove wastes, maintain inner stability (equilibrium), respond to environmental conditions, reproduce.

ii. Cells vary in complexity, with some having more organelles than others. However complex they are, cells must have ways to perform the functions of living things.

iii. Cells are chemical factories, and are the result of self-assembly of molecules. The intelligence behind cells is innate in the atoms, not the product of a self-aware director of activities.

iv. Cell theory – All cells alive today came from other cells. Things that do not have cells are not alive, although viruses are a gray area.

  1. Consider participation structures and tasks for students. This next section I do not do necessarily in order, although I usually think of tasks, and then review my resources and choose participation structures.
    1. Standards. I will look at National and GPS. These tell me what some of my assessment goals will be.

i. Gaps

1. The GPS are particularly troubling here, because they do not ask students to understand anything much about macromolecules, and certainly nothing about molecular structure. I know from my own experience that 7th graders are capable of learning this, and the absence here is extremely problematic for getting the big picture. This means that understanding structure and function of cells is difficult for students to understand. Here I will consider whether I will need to talk about that is not REQUIRED by the standards.

2. Chemistry of 3 basic macromolecules

a. proteins

b. carbohydrates

c. nucleic acids

    1. Likely misconceptions and cognitive difficulties.

i. How do plants and animals use these 3 basic molecules? I know this is a major misconception area. Cells are structures made mostly of proteins, some lipids, some sugars, a few odds and ends of other chemicals. Animals use calcium carbonate in bones, shells and exoskeletons in order to provide shape and leverage for muscles (when they have them). Plants use sugars (cellulose) to make structures such as stems and leaves. The various types of animal and plant support structures are outside of cells, not part of them.

ii. The most obvious cognitive issue is one of scale. Cells mostly (except for eggs) are invisible to the naked eye.

    1. Assessment.

i. Multiple choice test about cell structure and function. I think a well-designed multiple choice test is quite appropriate here.

ii. Reports of investigations in notebooks.

iii. Responses in journal narratives (self-assessment).

iv. Creative cell structure and function project. Could be a skit, a poster, a short-story, a song, or…

1. This task will require deeper understanding and assess whether students have created new knowledge.

2. Also will assess problem-solving, collaboration and social skills.

v. Ongoing formative self-assessment.

    1. Tasks

i. Students must look at cells under the microscope.

ii. Students must understand the scale of things under the microscope.

iii. Students must tie the idea of cell organelles to functions of living things.

    1. Development of ideas. Now I’m starting to bubble with ideas—when they occurred to me before, I purposely ignored them. I’m going to think about how ideas will build into a big picture for students.

i. Start with an activity about defining characteristics of living things.

ii. Do an inquiry about scale

iii. Do an inquiry about looking at cells in living things.

iv. Tie functions of cells to characteristics of living things.

v. Children’s book project

vi. Multiple choice test.

    1. Participation structures. What is the benefit of using each, and how will this advance my goal of all students inquiring and learning?

i. Whole group

1. Purpose

a. Get students’ thinking onto public floor.

b. Create shared new knowledge.

2. Format

a. Students’ talk not teacher talk. Teacher’s role is facilitator of the conversation, making sure everyone’s voice is heard, and that important contributions are noticed.

b. Record all contributions and post in room.

ii. Small group

1. Purpose

a. Every student talks and is listened to.

b. Groups provide ZPD for all members.

c. Each student contributes important skills.

2. Format

a. Students given open-ended task, with defined responsibilities and roles.

b. Self-assessment of group interactions, sense of responsibility for functioning.

c. Ideally, groups will have slightly different task, so that task becomes more important.

iii. Individual

1. Purpose

a. Private time for reflection, writing

b. Assessment of individual learning

2. Format

a. Seatwork

b. Multiple-choice test.

    1. Resources

i. I will consider what resources I have available.

ii. I will figure out how to get what I need if I don’t have it.

Task 1: More than meets the eye. All living things are made of cells.

Part A: Day Before

I: Give NSTA pre-assessment task on living versus nonliving. T collects and reads through Ss’ responses. Decides on groupings of 4 for the next day. Goal for groupings is to put Ss with similar status but different answers together, may not be completely possible.

Part B:

Purpose: Uncover prior knowledge about living and non-living, allow Ss ample opportunity to talk about and revise their understanding. Derive definition of living and non-living.

Learning goals: Ss will be able to describe characteristics and functions of living things.

WG: Tell Ss you have read their pre-assessments and see that there are differences of opinion. Tell Ss you think it will be useful for them to talk in the small groups about their answers, and they are free to revise their opinions after the conversation. Remind Ss if you tell them the “right answer” they might forget, but if they figure it out in the group, they are more likely to remember. Also tell them you think they are “good thinkers” and will be able to come to the right conclusions. Remind Ss it is ok to change their minds, and that scientists revise their conclusions when they see new evidence. If Ss want to revise their opinions, they must give a good rationale.

SG: Give the groups written directions. Assign roles: Facilitator, Recorder, Reporter, Timekeeper. Facilitator will make sure every person is heard, recorder will make a record of what the group said, the reporter will report to the class, and the timekeeper will have a stopwatch and let the group know when time limits are up. The task will have time limits per question. Groups must report if there were any questions on which everyone agreed right away, questions on which nobody agreed, and questions on which people revised their opinions. The recorder will have a worksheet to record this information.

WG: T will make a chart Definitely Living, Definitely Non-Living, Not Sure. These will be on cardboard and can be moved around. If there are errors, T will leave it for now. Assign pairs for think-aloud, and hand out reading. Make sure weaker readers have support of stronger reader.

SG: T will have grade-level reading handouts about living and non-living. One will be shared by all groups, and a second will contain information about one of the Not Sure organisms, or one of the erroneous classifications. This means thinking in advance about likely wrong or unsure categorizations, and being ready with information. Ss will do a think-aloud with a partner.

I: Ss will write a paragraph about whether they have changed their minds about where to put any of the items, and why this did or did not happen.

WG: Ss will report any proposed changes to the chart. T will ask class if anyone can make generalizations about functions and characteristics of living things.

I: Writing prompt in journal: What did we do in class today? Why did we do it? What do you still not understand?

Part C:

Purpose: Introduce microscope skills, introduce idea of small scale invisible to the human eye. Tap into prior knowledge about objects.

Learning goals: Ss will be able to name several items that have lenses. SS will describe how microscopes are scientific tools for looking at very small objects, and what kind of information they provide. Ss will begin thinking about scale. Ss will develop scientific drawing skills. Ss will reflect on how their everyday world might not be what they thought it was. Ss will ask questions about the structure of the living things they observe under the microscope.

Organization of Groups: We will use the 4-2-1 system from SEPUP. 4 students are a group, 2 students work in pairs, each pair with own equipment. 4 responsibilities in the group: Reporter, Materials Manager, Questioner (only one of the 4 allowed to ask T for help), Recorder. The “1” in 4-2-1 refers to each individual being responsible for writing in their lab notebook as instructed. Ss will already be familiar with the 4-2-1 system and will not require instruction for this activity.

Rules for Notebooks: The notebook is the individual creation of each S and they may use whatever format they like. T passes out handout of what must appear in write-up, which is pasted into notebook, and reminds Ss s/he must be able to find everything or they will lose points on their grade. The lab notebook is essentially a record of everything that happened in class and includes whatever Ss think is important, probably including social interactions. T corrects notebook using sticky notes and does not write in Ss’ notebooks. If documentation is necessary, T Xeroxes notebook.

WG: Ask Ss what a lens does. Where have they seen lenses? What types of things in their lives have lenses?

SG: After two examples, ask Ss to pair up and make a list of anything else they can think of that has a lens. 1 or 2 minutes. Pairs come together in quads and make a combined list. Spokesperson for each quad reports to class. Teacher compiles class list, writes on computer, to later be transferred to poster paper.

IND: Ss write in lab notebook three or more objects in their experience that have lenses, and what each does.

WG: T shows Ss how to carry a microscope. Asks Ss to get one microscope per pair. Asks Ss to examine microscope and find lenses. Asks Ss what the numbers might mean.

IND: T holds up a piece of Elodea leaf and asks Ss to predict what it would look like under a microscope. Ss write and draw prediction in notebook/journal.

WG: T tells class how to put specimens on a slide, where to put the slide, how to turn on the light. This is also on the handout. T asks Ss to suggest important special safety rules for this lab. (General rules will be posted in the room, and it might be good to revisit them.) Writes down safety rules on poster paper with name of person who contributed rule. E.g., “Angel suggests, ‘Don’t fool around so you don’t knock the microscope on the floor.’” “Be careful with glass so you don’t cut yourself. (Marc).” Ss write special safety rules in their lab notebook. Teacher gives page of directions for making drawings and using the microscope.

SG: Pairs of Ss get piece of Elodea, place on slides, and look at it under microscope. Teacher circulates and assists as necessary. If Ss ask questions which are in the written instructions, directs them to read it to each other. Teacher will look at what Ss are seeing, adjust focus as necessary, point out groups that have interesting things to look at, including air bubbles and pieces of dirt. No one may ask a question of the T unless everyone in the group has the same question. Ss may look at other groups’ specimens if there is time. Ss must produce a drawing of their own specimen in their notebooks. If some Ss finish early, T will have several different small objects available for viewing and drawing.

I: When all are finished viewing, each S looks at prediction and compares with what s/he actually saw.

SG: Discuss what each person saw, and the difference between the prediction and the observed.

WG: Reporters share what the difference between the prediction and the observed was in their groups. T writes observations on poster paper, e.g., “Shaun says he predicted he would just see green, but what he saw was like little bricks with green circles in it.”

I: Teacher asks each S to write in notebook what questions he has about looking at cells under the microscope, or questions about what s/he saw.

SG: Ss compile list of questions on post-its. Recorder writes each one on sentence strip. Other Ss answer writing prompt.

WG: Reporter comes to front of room and reads the group’s questions to the class. T posts questions. End of 90 minute class session (or beginning of next day) with discussion, what do you think the parts of the leaf were? Were the Elodea leaves living? What is the evidence for this, including what you saw under the microscope?

I: Writing prompt in journal: What did we do in class today? Why did we do it? What surprised you about looking at leaves under the microscope? What do you still not understand?

Homework: Ss will bring to next class any items they want to look at under the microscope.

FUTURE LESSONS (not written yet):

1. Review of questions. T gets the following question onto the table: Does everything have smaller parts when you look under the microscope. Inquiry for 1 class period, open-ended, Ss will examine objects they brought under the microscope, can trade. WG: T will develop the idea of cells.

2. Review of questions. Day devoted to idea that all living things have cells. Ss will read history of cell theory using literacy strategy. Ss will decide whether objects they brought are living. Compare to NSTA pre-assessment, discuss.

3. Review of questions. SG activity to develop a list of characteristics of living things. WG discussion.

4. Review of questions. Review of SG activity on characteristics of living things. WG Show picture of plant cell, diagrams. Relate labeled parts to characteristics of living things. Animal cell diagram, relate to difference in characteristics of plants and animals. Provide list of cell organelles. IND (could be pairs) give Ss list of cell functions, they design a cell with the structures that will allow the cell to carry out these functions.

5. Start creative project, 3 days.

© 2010 Victoria Deneroff PhD. May be used by K-12 educators, but not republished in any form.