The Cell Lab: Working with Microscopes (Day 2 of 3)

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Objective

SWBAT independently and effectively use a light microscope to view and identify cells.

Big Idea

Check out my version of the classic microscopes and cells lab experience using an engaging online tutorial and encouraging students to take their own micrographs to share!

Notes for the Teacher

This is a three day lesson series focusing on microscope skills and cell organelle identification and comparisons.  

On Day 1, students review the different types of microscopes and why/when we use them.  We then work through an online tutorial to build basic microscope skills.   Standards: SL.9-10.1, RST.9-10.3

On  Day 2, students practice their microscope skills using prepared slides of pond life.  They then follow a simple procedure to create wet mount cheek cell slides and answer questions about cell types and organelles. Standards: SL.9-10.1, RST.9-10.3, XC-P-HS-1, XC-SF-HS-2, SP4, SP8

On  Day 3, students look at onion cell slides they wet mount themselves and discuss the differences between plant and animal cells.  Standards: SL.9-10.1, RST.9-10.3, XC-P-HS-1, XC-SF-HS-2, SP4, SP8

Every biology teacher does some sort of microscope introduction lab and in the past, I found that I was running around breathlessly to every station helping each individual lab pair to adjust their focus and work with their microscopes.  Since I began to use the 15-20 microscope tutorial, this no longer happens.  I highly recommend it the Virtual Urchin website microscope tutorial and other resources and am eager to hear your experiences using the online tutorial with your classes.  

My goal here is for students to get a sense of how to use a microscope, what a cell actually looks like, and to attach basic cell and microscope vocabulary to their experience creating and viewing slides.  

I extended this lab from two days to three to allow for the tutorial and for more time for discussion and comparison of the kinds of things lab pairs were doing and seeing on their individual microscopes.  As an additional interest, I asked students to experiment with taking photos of their favorite cell slide field of view and send it to me to share with the class.  This idea was inspired by our local public television's education webpage on the KQED website; I saw a short video clip there called The Amazing Life of Sand and thought it might be a nice to way to bring in appropriate student device use as a way to gather evidence of their work to share out as a class on Day 3.  Students were highly engaged with this aspect of the activity and to make the photo session work, they had to really dig into the vocabulary of the microscope parts in order to give and act upon suggestions each of them had to enhance their photo taking abilities.  I loved this unintentional positive side effect of introducing the photo angle to our straightforward lesson.  

 

The Classroom Flow: Introducing the Lab

15 minutes

1.  Before class begins, place 1-2 copies of the Cell Lab directions document onto each lab table.  Also place one copy of the labeled microscope diagram on each lab table.   

  • Note:  I like to put each one into a plastic sheet protector to ensure that they are not soaked or taken at the end of each class session.

2.  When students come into the classroom, remind them that today is the second day of their three day cell lab and that yesterday's tutorial will be helpful as they work through their directions to view and make slide mounts.

3.  Pass out the Cell Lab Data and Analysis document to each student.

4.  Review your expectations for microscope drawings:

Use of color

Labeling

How to determine magnification

What is the 'field of view' and what exactly do I draw inside it?

5.  Request that each lab pair take a photo of their favorite microscope field of view image to share with me electronically.  

  • Note:  I found that adding this element enhanced student conversation about how the microscope works and its components.  It also encouraged quite a bit more collaboration and comparative discussions across lab pair groups as they looked at each other's photos, brainstormed ways to enhance their photo taking technique, and asked questions about what exactly was in the photo.

6.  Review the lab procedure for the next two days with students:  

Part A--prepared slides (to complete today)

Part B--cheek cells  (to hopefully complete today)

Part C--onion cells (to do tomorrow)

7.  Remind students of proper microscope carrying procedure: one hand holding the arm, one hand supporting the base.

8.  Ask students to move to their lab tables and begin their microscope exploration.

  • Note:  I typically keep a set of computers in the classroom this day so that students may complete the online microscope tutorial if they did not finish it yesterday.  It takes about 15 minutes.  

The Classroom Flow: Lab Group Work

35 minutes

1.  When students first begin to work with their partners, if possible hang back and let them work through their initial questions together as a team and instead focus on assisting students in finding the materials they need for each section of the lab activity.  

 2.  You will see students engaged in the activity in many ways:  viewing slides under the microscope and collaborating with other students, and taking photos of their microscope fields of view.  Take the time to express interest in their photos and point out various other lab pairs that have interesting specimens on their microscope stage or captivating photos and invite the pairs to show each other what they are working on.  Tapping into their curiosity is the key to increasing their persistence while learning to navigate their microscope equipment!

3.  As you circulate around the room, observe and listen in to student conversations and group work.  If student groups do not have questions for you to answer, ask questions like

  • What kind of cell do you think that is?
  • How do you that is a …?
  • What does every microscope sketch need to include?
  • How do you find the magnification on this microscope?  Is it different from other microscopes?   How can you tell?
  • Show me an example of a ….

4.  The student work sample for page two of the document show a typical student response set to questions related to basic cell terminology and microscope procedures.  The student work sample for page three show labeled drawing of microscope fields of view for this activity.  I can see that I will need to review how to determine the magnification used for each drawing (multiple the magnifications of the ocular and objective lenses).  The student micrographs consisted of both protist/animal and plant specimens.

And now on to Day 3!