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Microbes

Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne Erdmann, MS, Sonia Rahmati Clayton, PhD, and James Denk, MA.

Magnifying Plant Cells

Procedure

1. Begin by showing students a transparency of the “Magnifying Cells” sheet. Explain that the structures visible in each frame cannot be seen without magnification. Let students ask questions about what is visible in the images. Tell students that they will be making their own slides to observe the tiny structures, called “cells.” 

2. Point out the labeled parts of the cells on the transparency. Help students understand that they will look for similar structures in their specimens. 

3. If necessary, review microscope use with all students (see Activity 2, “Tools of Magnification"). If available, use a micro projector or video attachment on a microscope to demonstrate how to view cells, change magnifications and make observations. 

4. Have students work in groups. Tell them to follow the instructions on their “Preparing & Viewing Slides” cards to prepare their slides.

5. After each group has created both slides, have students take turns observing and drawing their specimens (noting the magnification being used). Have students first examine the cells using low power and then refocus using a higher power objective. Instruct students to make detailed drawings and to label any cell parts that are recognizable. Tell students that some parts of a cell may not be visible when viewed under a microscope. Allow 10–20 minutes for this step. 

Note: Have students determine the total magnification by multiplying the power stamped on the eyepiece (for example, 10x) by the power of the objective.

6. Students usually will be able to observe the cell nuclei in the stained onion skin cells. They also should be able to observe cell walls and cytoplasm in both kinds of cells, and to identify chloroplasts in the Elodea cells.

7. Display the “Magnifying Cells” transparency for students. Encourage groups to discuss among themselves what they observed. Ask, Are all the cells about the same size? Could you see a dot (nucleus) inside all the cells? If not, why?

8. Explain the names and functions of the cell structures that students observed and drew. 

9. As an assessment, ask students, What are the major parts of the cells you observed? (Structures most likely to be identified include cell wall, nucleus, chloroplasts and cytoplasm.) You also might ask, What similarities and differences did you observe between the two kinds of cells? Students can record responses in their science notebooks or turn in their answers as assignments. You also may question each group individually. 

10. Allow students time to add information to their concept maps. Explain that while the class has examined some cell structures of multicelled organisms, many organisms consist of only one cell. Students will have opportunities to learn more about single-celled microorganisms in later activities. 


Funded by the following grant(s)

Science Education Partnership Award, NIH

MicroMatters
Grant Number: 5R25RR018605