The Cell Lab: Working with Microscopes (Day 3 of 3)
Objective
Big Idea
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: Continuing Microscope Work
1. Remind students that this is Day 3 of a 3 day lab focusing on microscope use and cell identification.
2. Ask them to take out their Cell Lab Data and Analysis document and confirm that you have laid out the Cell Lab directions and microscope labeled diagram documents in sheet protectors on each lab table.
3. Outline the flow for today: At this point, students should have completed Part A (prepared slides) and most likely they will have also completed Part B (cheek cells). Tell students their job is to make sure both parts A and B are completed and then move on to Part C, making and viewing onion cell slides.
4. Review the lab materials area: Part A, Part B, Part C, and slides and coverslips.
5. Review the expectations for microscope drawings: field of view, magnification, color, and labeling
6. Remind students of the proper way to hold and transport a microscope: one hand on the arm, the other supporting the base.
7. Ask students to move to their lab tables and begin their work.
- Note: If you had a good experience yesterday with the additional photography/image section of this activity, encourage students to take and send you photos of their favorite microscope image today. You can use them during the final review/wrap up activity.
8. After about 30 minutes, remind students that you will be meeting as a large group in ten minutes to wrap up the activity by sharing out challenges, successes, surprises, and questions.
The Classroom Flow: Wrapping Up
1. Write the following prompt on the board:
Share out some of your group's
Challenges
Successes
Surprises and/or questions
2. Use the spokesperson protocol for a quick lab group check in and large group share out. The kinds of prompts you can use to help support student reflection include:
- Was it difficult to tell the difference between prokaryotic and eukaryotic cells? Plant vs. animal cells? How could you differentiate between them?
- How easy was it for you to get your slide view in focus? How did you make that happen?
- were you able to see chromosomes or other organelles? Why do think that might be?
Whenever possible, bring the conversation back to either the content goals or the process of using the microscope. Asking students to reason out why their microscopes could or couldn't reveal specific organelles can help students figure out ideas related to size/scale, color, and equipment weaknesses like the strength of the light and the number of objectives.
3. If you have time, pull up some of the most impactful student photo images to share/discuss. If you don't have time to do that today, you may choose to do so the following day or at a later time as part of a unit review.
4. Before the class ends, remind students of due dates for their written work and microscope drawings. The student work sample for page four of the cell microscope lab shows that this student was able to connect the work we did with the microscopes to the broader themes of cell organelles and eukaryotes vs. prokaryotes. This student also sent me a note with a copy of her favorite micrograph!
