Lesson 10 of 12
Objective: Students will be able to develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.
This lesson asks students to create two models that demonstrate how the cell membrane can contribute to cell function. Students use garbage bags and wads of paper to model diffusion and use plastic sacks, strings, and Starburst to model endocytosis.
This lesson is specifically designed to address the following NGSS and Common Core Standards:
MS-LS1-2 Develop and use a model to describe the function of a cell as a whole and ways parts of cells contribute to the function.
CCSS.ELA-LITERACY.RST.6-8.10 By the end of grade 8, read and comprehend science/technical texts in the grades 6-8 text complexity band independently and proficiently.
CCSS.ELA-LITERACY.RST.6-8.7 Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table).
Scientific and Engineering Practices:
Asking Questions and Defining Problems (SP1): Students at any grade level should be able to ask questions of each other about the texts they read.
Developing and Using Models (SP2): Develop a model to describe unobservable mechanisms.
Systems and System Models: Models can be used to represent systems and their interactions—such as inputs, processes and outputs—and energy, matter, and information flows within systems.
Stability and Change: Systems in dynamic equilibrium are stable due to a balance of feedback mechanisms.
Begin class by asking, "What are you going to learn today?". Students should respond by referring to the Essential Question, "How do cells contribute to the function of living organisms?". This EQ can be referenced both on my front board as well as on their Cells Unit Plan.
Have students get out their Cells Unit Plan. Explain that their focus of this particular lesson is Skill 3 (I can create a model that shows the relationship between cell structure and function) and Skill 4 (I can identify important materials and processes that are required for cells to function). Have students read the skill and self-assess where they stand in their level of mastery in this skill. Students rank themselves on a scale of 1 to 4 (4 being mastery).
As the unit moves forward, I have the students continually self-assess on each skill. In my class, this will be the students second self-assessment, so they change their scores if they feel that their learning has improved. Check out the student's unit plan below to see how students update their mastery level with each lesson.
In the previous lesson, the students read the first page of the Cell Transport reading. In that lesson, the teacher modeled how to implement some reading strategies geared specifically towards science.
During this lesson, the students apply the strategy on their own and climb the Ladder of Discourse. The Ladder of Discourse is a strategy I use in my class to help students think critically as they read. For middle school students, informational reading can just become words on a page. The Ladder of Discourse is a way to help students recognize what they should be thinking about as they read so that they can gain an understanding of the text.
The levels of the Ladder of Discourse are "Tweets" (text to self connections), "Huh?'s" (questions or concepts they do not understand), "Found It" (finding answers to questions through context clues or finding science answers), and "Discourse" (combining ideas to think beyond the text). The resource Ladder of Discourse: Description of Rungs provides background about the "rungs" students use when reading.
For middle school students, thinking critically during reading is a challenging task. However, being able to think beyond the text is key to real understanding of scientific concepts. This "thinking beyond the text" is what we call the rung "Discourse". I have found that the NGSS has provided us with an invaluable tool in the Crosscutting Concepts. These provide students with themes that can guide their critical thinking. As they read, students have their Ladder of Discourse: Description of Rungs document out so that they have a description of the Crosscutting Concepts next to them with the CCCs fresh in their mind. While reading, they try to make connections to the CCCs. This could be in the form of a statement, idea for an experiment, a prediction, or a question. In order to do this, students have to slow down when they read. Every 2 - 3 sentences they stop and think about what connections they are making to the text and they document their thinking by "talking to the text".
I have found that with the implementation of this strategy, my students depth of understanding from reading has dramatically increased. As students read, they "talk to the text", to document what they are thinking.
Now, I will say, this strategy takes practice! It is not a magical strategy that makes reading easy. It is a tool, however, that provides students with a structure and thought process for critical reading. If you stick with it, I promise you that you will see an increase in the depth of thinking your students demonstrate while reading. As another tool to help with this strategy, I have included a resource called Ladder of Discourse Sentence Starters that I used with my students when I first began implementing this to get them thinking about the Crosscutting Concepts.
Take a look at some of the ideas and questions that my students generated during this reading. None of the comments on the sticky notes were stated in the text, it was all their own connections and conclusions beyond the text. They are all ideas the students connected to because they were thinking about the Crosscutting Concepts as they read.
Cause and Effect:
Stability and Change:
Systems and System Models:
Energy and Matter:
Station 1: Membrane Mania
- Using a garbage bag with holes in it and 20 wads of paper, create a model that represents diffusion.
- Using the model you just created, change the concentration outside the cell. Model how the system might change as a result.
Station 2: Endocytosis - Enter the Sugar!
- Using a plastic sack, scissors, string, and a Starburst candy, model endocytosis. The plastic sack represents the cell membrane while the Starburst represents a molecule using active transport to enter the cell. You can stick your had in the bag. Your hand represents the energy that is needed for active transport to occur.
- You must show the teacher your bag once you think the Starburst has entered through endocytosis! You must be able to explain the model to the teacher. In addition, be ready to explain what you would do if you were asked to show how you might model exocytosis.
After students have created their models, have students go through the discussion questions in small groups. Then, have each group share out to the whole group the key points that were discussed.