Summer Research Program for Science Teachers
Emerson High School, Union City, NJ
August 2004
Cell Size Changes
Teacher Section
Purpose: The purpose of this activity is to allow students to understand the behavior
of living cells treated with different types of stimuli.
Content Objectives:
The student will be able to:
· Identify the function and structure of semi-permeable membranes.
· Predict how processes at the cellular level affect the functions and characteristics of an organism.
Process Objectives:
The student will be able to:
· Identify and explain structure and function.
· Use microscopes to make observations.
· Use computer software to measure differences in structure.
· Apply process of scientific investigation.
· Show that scientific knowledge must be based on evidence and is subject to modification.
Grade Level: This activity is geared towards 9-12th grade Biology students working in
cooperative groups.
National K-12 Unifying Concepts and Processes
Science Systems, order, and organization
Education Evidence, models, and explanation
Standards: Change, constancy, and measurement
Form and function
Grades 9-12
Science as Inquiry
Abilities necessary to do scientific inquiry
Understanding about scientific inquiry
Life Science
The cell
Behavior of organisms
Science in Personal and Social Perspectives
Personal and community health
History and Nature of Science
Nature of scientific knowledge
Time This lesson will take several days, depending on length of class time.
Required: For a traditional 45 minute class schedule, the lesson can be divided into
four or five days.
Prior This activity is designed for students who have a basic knowledge
Knowledge: of cells, permeable membranes, osmosis, use of the light microscope,
and use of the Excel spreadsheet program.
Including All Students:
This lesson appeals to a variety of learning styles:
· Visual (viewing movie, viewing cell changes, Web Search)
· Auditory (discussions & presentations)
· Tactile (experiment & presentation preparation)
Safety: Normal laboratory safety precautions should be followed. The teacher should approve experiments designed by students, prior to its implementation, and supervise experiments while being carried out.
Materials:
· Computer with:
o Internet access
o Scion Image (PC or Mac - download FREE)
o Microsoft Office Excel
· LCD Projector and screen
· Microscopes with still photograph capabilities
· Wet mount unicellular microorganism slides
· Pipettes
· Beakers/Test tubes of any safe solution in lab, including but not limited to:
o Glucose solution
o Saline solution
o Cold water bath
o Hot water bath
o Bleach
o Ammonia
o Detergent
· Overhead Projector & Transparencies (poster boards can substitute)
Preparation:
Day One:
· Set up computer with LCD Projector.
· Set up Internet link, http://www.brainpop.com prior to class
§ Click on ‘Play a movie’, upper right corner of screen, and select ‘Cells’. (Warning: Without a subscription, you will only be able to view two movies per day. If you have more than two biology classes, you may need to begin this lesson on different days).
· Download Scion Image (PC or Mac) free of charge.
§ Visit Scion Corporation’s website http://www.scioncorp.com click on ‘Download Scion Imaging Software Now’. Choose either PC or Mac compatible software to download.
§ To measure cell sizes:
1. Open the Scion Image program and click on ‘Analyze’ in the tool bar. Then select ‘Options…’, make sure that the only Measurement Options that are checked off include: Area, Perimeter/Length, Ellipse Major Axis, and Ellipse Minor Axis; then click ‘OK’.
2. Go to ‘File’ in the tool bar and select ‘Open’. Open the file (picture) that you would like to measure. If the image is too large, go to ‘Options’ in the tool bar and select ‘Scale to fit window’.
3. In the ‘Tools’ tool bar, click on the third image down on the right, it looks like a bent square. Use your mouse to measure the cell by clicking a line fully around its perimeter.
4. Go to ‘Analyze’ on the tool bar and select ‘Measure’. Click on ‘Analyze’ again and select ‘Label selection’.
5. In the ‘Tools’ tool bar, click on the fifth image down on the right, it looks like a line with an arrow. Use your mouse to click on one end of the cell and draw a line to measure its’ length.
6. Go to ‘Analyze’ on the tool bar and select ‘Measure’. Click on ‘Analyze’ again and select ‘Label selection’.
7. Use your mouse to click on one end of the cell and draw a line to measure its’ width.
8. Go to ‘Analyze’ on the tool bar and select ‘Measure’. Click on ‘Analyze’ again and select ‘Label selection’.
9. Go to ‘Analyze’ and select ‘Show results’. A window should appear showing the three measurements you have just taken. (Note: These measurements are in pixels, but may be converted into microns, see extension activities below).
10. Go to ‘Edit’ in the tool bar and select ‘Copy measurements’.
11. Open a new Excel spreadsheet and paste the measurements. (Make sure to create a data table, which includes: Cell Number or label, perimeter, length and width).
12. Return to Scion image, go to ‘Analyze’ and select ‘Reset’, this erases your previous results and allows you to take the next set of measurements.
13. Make sure to save all results on the Excel spreadsheet.
Day Two:
· Prepare wet mount slides and solutions prior to class.
· Prepare microscope or microscope with still photograph camera
Day Five:
· Make arrangements for computers with internet access.
Procedure:
Day One
Engage Students
1. Students are shown a movie clip from http://www.brainpop.com to review cells and their structures. Students can also take the ‘Cell Quiz’ to show their knowledge. (10 min.)
Explore Concepts
2. Students work in groups of three to four. Students are asked the following question: “How do different stimuli affect the cells of living things?” They are told to develop a hypothesis and design an experiment, using the materials provided, to support their predictions. (10 min.)
3. Students design an experiment to test their predictions. Their experimental design must include a control group, variables, a data table, and be teacher approved prior to implementation. (10 min.)
4. Students are shown, using the LCD projector, how to use Scion Image to measure cells. (15 min)
Day Two
Experiment
5. Students implement their experiment with teacher supervision. They should take pictures of both the control group and experimental group.
(30 min.)
6. Students should label and download cell images onto the computer for
analysis. (15 min.)
Day Three
Analyze Data
7. Students measure their cells, using Scion Image, and copy the measurements into a self-made data table, on the Excel spreadsheet program, for comparison. (20 min.)
8. Students should prepare overhead or PowerPoint presentations for the class which show their experimental design and results, including data tables, graphs comparing control and experimental groups, and conclusions. They are given a Self-evaluation Rubric to insure they cover all the points required for the presentation. (25 min.)
Day Four
Explain Results
9. Students present experimental design and results to the class. All students must participate in some aspect of the presentation.
(40 min.)
10. Students are assigned lab write-up for their portfolio. (5 min.)
Day Five (optional)
Elaborate with Further Investigation
11. Students are given a Web Search (attached) assignment to do online in pairs. (30 min.)
Evaluate Activities
12. Students share the information learned from their online search.
(20 min.)
Suggestions for Assessments:
· Class participation – cell quiz & discussions
· Self-evaluation rubric
· Presentations
· Lab write-up
· Internet Web Search
Extensions:
· Copy Grid Paper (attached) onto a transparency, cut up into squares, and place over wet mount slides, in order to view and measure cell size changes without using Scion Image. The students can measure the sizes of the squares to estimate actual lengths.
· Have students video tape cell size changes and put together short films.
· Convert pixels into microns, in order to compare actual cell size changes:
§ Use the attached Grid Paper by printing it and copying it onto a transparency. First measure the length of one box, on the grid, using a millimeter ruler (Note: to convert millimeters to microns: 1 micron = 10-3 millimeters). Then, cut the transparency into a size small enough to place on the stage of a microscope. Next, take a picture of the same box under a microscope (Note: Results will vary at different magnifications, so make sure your use
of magnification remains consistent). Download the picture onto your computer and using the Scion Image procedures, mentioned above, measure the length of the box in pixels. Finally, divide the number of measured microns by the number of measured pixels, to find the Micron:Pixel Ratio.
§ Open the Excel Cell Analysis Spreadsheet and type the above ratio into the box (cell) at the very top of the spreadsheet, next to Micron:Pixel Ratio.
§ Students can then paste their cell measurements, in pixels, from this lesson, into the ‘Scion Image Results’ column. The converted cell sizes, in microns, should appear in the column labeled ‘Converted Cell Sizes’.
§ If there is time, have your students find the Micron:Pixel Ratio, to practice conversion and calibration.
References & Resources:
http://www.brainpop.com – BrainPOP, Mount Kisco, NY 10549
http://www.scioncorp.com – Scion Corp., Frederick, Maryland 21701