The image of the thinking student indicates a student activity.

Cells and the Cell Model

1 - Measuring the Cell Model
Cells are tiny. The average human cell is about ten micrometers across and it is estimated that there are around ten trillion (10,000,000,000,000) cells in the human body. Write this on the board or overhead. Ask students what they would guess would be the size of an average cell. Smaller than the drawing they used at the museum? Of course!

Review the student measurements. Review with students why it takes more cell drawings to tile the larger cell model than to use the cell drawings to cover the width.

Difference between length and area.

The giant cell model is about five times wider than the picture of the cell. The giant cell model at the museum is one million times bigger than a human cell. If the human cell was as big as the period at the end of this sentence then the cell model would have to be as big as 10 Diplodocus skeletons lined up tail to nose and the cell drawing would have to be as big as 10 SUV's lined up bumper to bumper! Human cells are tiny!

Because cells are so small, scientists use models of cells to help them in their research. These models can be computer programs or 3-D cells made from plastic.

Mathematics allows scientists to more accurately describe what they observe.

Disease and Bacteria

2 - Measuring a Sneeze
One cause of disease is bacterial infection. Another is viral infection. Bacteria and viruses can travel from place to place with human assistance, like a sneeze or on hands that touch one surface and then another.

Ask students to look at their data from the museum activity, Measuring a Sneeze. What do they notice about their measurements?

Ask students to share how they measured the sneeze.

Mathematicians like Claudia Neuhauser use math to develop new understandings about the behavior of organisms, like bacteria, through the use of models. The pre-visit activity on binary fission is just part of the story. There are other factors that affect the size of a bacterial colony and the rate of growth. Try this game for students to get a better idea of how bacteria interact with the environment as they multiply.
Modeling Bacteria Growth: A more realistic model

Cells Alive contains background information on modeling bacterial growth and factors that will affect the growth patterns. Students will enjoy seeing the bacterial growth models and webcams.

What did the students learn about keeping healthy from these activities? Ask students to make a list of suggestions to help others know more about how to stay healthy.

Microscopes

Ask students to cut apart their museum pages to separate each magnifying tool.

Students can initial their drawings before they cut them up if they like.

Post all of the x5 (Body Hotel) microscopes together, post the x20 microscope views (Collections Gallery) and so on. Ask students to observe each collection of data.

How are the drawings different for each type of tool? How did the descriptions change from the x5 microscope to x400 in the compound microscope?

What happened to the image of the cell? The fly wing?

Which microscope was best to find the cell image on the slide?
Probably the x5 Brock scope (in Body Hotel)

Which microscope is best used to count the number of sections in a fly wing?

Which microscope helped you see the most detail?
X400 (how to use a microscope, x40 setting)

If students looked at the E.coli slide, discuss what they saw.

The pink color is a stain to be able to see the bacteria colony. Even at x400 it is difficult to see individual bacterium. Dr. Juni uses a x1000 microscope to observe and count bacteria.

How many times bigger is it?

How does the size of magnification change as the strength of the microscope changes? Comparing Microscopes

Discuss with students: Why does the image using the microscope with x5 magnification cover 25 squares and not just 5?
Magnification increases the image in both width and length.(area)

Discuss: Dr. Billie Juni uses a microscope that magnifies x1000 so she can see bacteria! How many students would you need to work together to trace the outline for that microscope? How many squares would this magnification outline?
One million