Cells: Membrane and Nucleus Part 2
Lesson 3 of 8
Objective: Students will be able to use a computer model to plan and analyze an investigation about cell membranes
The purpose of this lesson is to review the scientific process with students while allowing them to further investigate the functioning of the cell membrane. By the end of the day I want kids to be fluent with the idea that the membrane is made of fats and proteins and that the proteins can serve as channels and gates to control what gets in and out of the cell.
Learning Goal: Understand how the cell regulates what comes in and out.
Essential Question: How does the number and type of channel impact the cell's functioning?
Students come in the room, get ready (get their stuff), get set (get settled in their seats), and engage in writing the learning goal and answering the essential question on the board.
For the hook today, I am going to have a cell membrane simulation up on the board. In this situation, there are only green molecules on one side of the membrane and two leakage channels.
I ask the students to consider how changing the amount of channels would change the time it takes for the green molecules to be evenly divided on either side.
We are going to be doing a lab investigation and writing a lab report today. The students have only written one lab report and I have a group of students that did not do well on that and will need support today. I open this lesson with an anchor chart to focus on writing lab reports. It is important to demonstrate my thinking on the organization and expression in lab reports so that student can understand the purpose of this type of formal writing.
After we go over some of the basic pieces of a lab report, I state the question we will be investigating today. "How would adding green leakage channels change the speed at which the green particles are equal on both sides of the membrane?"
I pull up the PhET simulation again and point out to students the parts we are thinking about. This provides a context because it emphasizes the primary information we are focusing on in our lab report writing today. At the end of this preparation, I give students a chance to talk with their partners about how they are going to investigate this question.
Since I already know (from yesterday's lesson) that I have a group of students that need support, this is a perfect time to set up a targeted instruction situation.
Most of my students will work independently on preparing the Title, Purpose, Hypothesis, and Procedure at their tables. The targeted group of students will do this with me in the back.
After students have had a chance to work, I pull the class back together and discuss the procedure. I let them brainstorm the procedure on their own, but I since this is not an inquiry lab but instead is more of a guided lab, I want them to follow a normed procedure.
We also get our data tables ready. Having the data tables ready is a great scaffold for students that are new to labs because it visually reminds them of what they have to do during the investigation.
Students work on the lab collecting their data. I circulate to different tables praising, prompting, questioning and leaving.
This is a video of two students doing the 1st round of the experiment.
Once the lab is done it is time for us to analyze the data together. Some students will be able to pick out the important data and draw conclusion, but many students would not be able to do this on their own yet. Instead, they are guided to a conclusion using a series of questions.
1. How long did it take for the green molecules to even out when you had one channel? Put data on the board.
2. How long did it take for the green molecules to even out when you had two channels? Put data on the board.
3. How long did it take for the green molecules to even our when you had four channels? Put data on the board.
4. What pattern are you seeing?
5. What time would you predict with three channels?
6. What time would you predict with eight channels?
7. How would we visually represent this data?
Using the Conclusion anchor chart, I norm the students in the process of conclusion writing and let them independently write their conclusions. I check in first with my targeted group to see how they were doing on this lab.
I am giving my students a project to complete at home during this unit. At the end of the unit we will display our projects in a cell museum. You can find the rubric and assignment here.
I like to check in with the students just briefly during class to remind them about the assignment and see where they are in it.
1) Students chose to do a model or a poster. I give students the option of a poster to support my free and reduced lunch students. They can still make a fabulous poster that looks the same or better than anybody else's with no financial outlay. Models can be made out of any material.
2) Students fill in the structure/function/picture/thinking chart. This is where students actually show understanding of the structure and function of cell organelles. Advanced students are encouraged to use metaphors as opposed to make a pure model, as this allows them to display more thinking. For example, one might say, I chose a whiffle ball for the nucleus because it has holes in it and could hold things inside.
As the cell models come in, I display them like a museum. Students are allowed to look at everyone elses and are encouraged to have discussions and give feedback using the rubric. Depending on time, students can vote on their favorites.
To wrap up this lesson, students read their conclusions aloud to their partners and identify the three sentence stems.
In this lab we found...
I know this because...
This makes sense because...