Draw students' attention to the key ideas by using posters or overhead transparencies.
Emphasize and discuss “What Cells Do” and “What Cells Look Like.”
Introduce this section with the Mini Activity: Using a Microscope to See Cells.
Make sure students have experience using a microscope. If the microscope uses a mirror and natural light, make sure students know not to point the mirror directly at the sun.
Emphasize the relationship between cells, tissues, organs, and systems.
Discuss the Mini Activity: Imagine a One-celled Human as part of an introduction to the problem dealing with the relationship of the surface area to volume.
Complete Activity 1-1: Why Are Cells Small?
Assign Mini Activity: How Changes in Surface Area and Volume Affect Cells with Different Shapes.
Relate the big ideas of this section to one another by discussing answers to the Review Questions.
Select appropriate Projects, if time permits.
At the end of the section, refocus students' attention on the key ideas.
Using a Microscope to See Cells Students examine cells from different tissues under a microscope and compare their similarities and differences in appearance and shape.
The existence of cells was first supported only after the discovery of the microscope. Do a library search to find out who invented the first microscopes and some of the scientists, besides Robert Hooke, who made important discoveries about cells.
Many scientific discoveries have resulted from one person exploring something just because of curiosity. Have you ever watched an ant trail for a long time or observed the patterns on the surface of the moon? Describe in detail your observations of something you've “studied” simply because you were curious.
What Do You Think?
Consider the very different functions of blood cells, nerve cells, and muscle cells. (a) Do you think all these cells look alike? Why or why not? (b) Do you think one kind of cell could perform the functions of another? Why or why not?
Relative Size of a Cell Students list parts of the body in order of decreasing size to help them get an idea of the relative size of cells.
Students list three of their favorite activities and explain in writing what kinds of cells they think are primarily involved in those activities.
Imagine a One-celled Human Students imagine how a one-celled human could function. They answer questions about how this cell would move, reproduce, exchange nutrients and wastes, and identify other problems that would result from its large size.