Accept all responses and write them on the board. Students may
mention any number of items. Some may be school-related, such
as binders, backpacks, pens, pencils, paper, and paper clips. Other
items may be more personal, such as water bottles, personal ste-
reos, and hair clips. Students may neglect items such as shoelaces,
zippers, buttons, fabric, eyeglasses or contact lenses, makeup, and
bandages. Discussion should reinforce the notion that humans
develop technology with a specific objective in mind. A related
concept is that a given task requires the right tool or tools.
4.
Pick a technology that students have mentioned. Ask them what
types of knowledge were required to develop that technology.
Students may not realize that technologies are generally developed
by applying knowledge from multiple disciplines. For example,
producing today’s audio devices, such as a portable CD player,
requires knowledge obtained from engineering, physics, mathemat-
ics, chemistry, and computer science.
5.
On the basis of previous discussions, ask students to rethink and
refine their definition of technology (from Step 1).
45
Student Lesson 1
Using Technology to Study Cellular and Molecular Biology
Students should mention that technology is a way of solving prob-
lems through the application of knowledge from multiple disci-
plines.
6.
Tell students to imagine that they live in the Stone Age. Their
only garment has been ripped and requires mending. How would
they do it?
Students first should recognize that the ripped garment is a prob-
lem requiring a solution. They should consider what technologies
they have available. The Stone Age was a period early in the devel-
opment of human cultures when tools were made of stone and
bone. Clothing consisted of animal skins or fabrics woven from
threads derived from plant fibers. Bones and sharp reeds were used
to make needles.
7.
Ask students how their approach to mending the garment would
change as time advanced from the Stone Age to the present. What
new knowledge would allow the development of new technology?
Student responses will vary, and some students may want to jump
Content Standard E:
directly from the Stone Age to the modern sewing machine. Slow
Technological design
them down and have them consider incremental changes in knowl-
is driven by the need
edge and technologies. They may cite the use of metals to fashion
to meet human needs
repair tools, like knives and finer needles. New knowledge of met-
and solve human
als and chemistry would help here. Later advances in engineer-
problems.
ing and mechanics would lead to the development of human-run
machines for assisting with repairs. Eventually, advances in physics
(electricity) and engineering led to the invention of modern sewing
machines. Similarly, advances in agriculture, chemistry, and engi-
neering produced better fabrics and threads. Students should derive
an understanding that technology advances through interactions
among multiple disciplines. While a problem may remain basically
the same over time (for instance, the need to make or repair cloth-
ing), advances in technology change how the problem is solved.
8.
Write the words problem and technology on the board. Ask students to use arrows to draw a graphic that represents the
relationship they believe exists between a problem and the tech-
nology to solve it.
Assessment:
Listening to students’
They can use arrows of any kind, and they should be prepared to
responses wil help you
defend their suggestions. The graphic should illustrate that a
assess their understand-
ing of the relationship
between problems and
technology.
46
problem does not drive technology unidirectionally, nor does tech-
nology exist solely in search of a problem to solve. Rather, these
two areas exist to support and drive one another. Solving problems
does require the development of new technologies, which can then
be applied to other problems. A graphic to depict this indicates the
cyclic relationship between the two:
Activity 2: Searching for Scale
1.
Biological molecules are small, but how small is “small”? Ask students these two questions:
a.
How do biological structures, such as cells, organelles, bac-
teria, and viruses, compare in size with one another?
b.
How do molecules compare in size with biological struc-
tures such as cells, organelles, bacteria, and viruses?
Accept all responses and write them on the board. Students will
explore these size relationships in the next steps.
2.
Tell students that they will now investigate the relative sizes of
different biological structures and see how close their estimates
of relative size were.
3.
Give each student a copy of Master 1.1, Searching for Scale. Work with the class to complete column 3, Size relative to cell.
The table with column 3 completed is as follows:
47
Student Lesson 1
Using Technology to Study Cellular and Molecular Biology
Biological
Actual
Size
Object
Mea-
Size
Structure Diameter Relative to Cell
Used to
sured
Relative
(in
Model
Size of to Model
Meters)
Biological Model Cell (the
Structure
Object
Room)
Cell
1 × 10–5
1 × 10–5
Room
10 m
10
= 1
= 1
1 × 10–5
10
Bacterium 1 × 10–6
1 × 10–6
Desk
1 m
= 1
1 = 1
1 × 10–5
10
10 10
Mitochon- 5 × 10–7
5 × 10–7
0.5 m
= 1
drion
1 × 10–5
20
Virus
1 × 10–7
1 × 10–7
0.1 m
= 1
1 × 10–5 100
(10 cm)
Ribosome 1 × 10–8
1 × 10–8
0.01 m
= 1
1 × 10–5 1,000
(1 cm)
Protein
5 × 10–9
5 × 10–9
0.5 cm
= 1
1 × 10–5 2,000
Glucose
1 × 10–9
1 × 10–9
0.1 cm
=
1
molecule
1 × 10–5 10,000
(1 mm)
H2O
1 × 10–10 1 × 10–10
0.1 mm
=
1
molecule
1 × 10–5 100,000
4.
Tell students that the information in columns 2 and 3 each can
be used to construct scales to describe the sizes of the different biological structures in the table. Ask students to define scale.
Accept all answers and write them on the board. Guide discussion
Content Standard A:
so that students realize that scale is a way to represent the relation-
Mathematics is essen-
ship between the actual size of an object (for example, its length or
tial in all aspects of
mass) and how that size is characterized either numerically or visu-
scientific inquiry.
ally. A scale is a series of ascending and descending steps to assess
either some relative (column 3) or absolute (column 2) property of
an object. In this case, the property being investigated is size.
5.
Ask students to try to visualize the 100,000-fold difference in
size between a cell and a water molecule. Can they do it? How
could they demonstrate this large size difference more easily?
Master 1.1, Searching for Scale provides the necessary clues for stu-
dents, since the heading of column 4 is Object used to model biologi-
cal structure. Students can use larger structures, such as a room, to
model smaller ones, such as a cell, to make size differences more
apparent and bring them into the realm of common experience.
6.
Ask two students to use a meter stick to mark approximately
10 m along both the length and width of the classroom.
48
It is okay if the classroom does not allow 10 m to be measured in
either or both directions. A distance of 7 to 9 m will still make the
point visually. However, for ease of calculations to follow, use room
dimensions of 10 m even if the actual dimensions are smaller than
that.
7.
Tell students that the space defined by 10 m wide, 10 m in
length, and the height of the room now represents a cell. In other
words, this space is now a model for a typical cell.
8.
Organize students into pairs and give each pair a ruler.
9.
Tell students that they will be searching the classroom for
objects that model the biological structures on Master 1.1,
Content Standard A:
Searching for Scale.
Recognize and analyze
alternative explana-
Explain that they will be looking for objects that have the same
tions and models.
size relative to the model cell (the room) that the actual biological
structure has to a real cell.
10. Ask students to look at the last three columns on Master 1.1,
Searching for Scale. As an example, a desk measuring 1 meter
high is provided as a model for a bacterium. Important points are
as follows:
Assessment:
Circulate around the
1
a.
A bacterium is the size of an actual cell (column 3).
room, noting whether
10
students understand
1
b.
Similarly, the desk is
10 the size of the model cell, the
the mathematics
room (1 m compared with 10 m; columns 4 and 5).
involved in scaling
objects for this activity.
c.
Because it is of the correct scale, the desk can be used to
model a bacterium if a cell is modeled by a room 10 m
across.
11. Instruct student pairs to locate items in the classroom that can
be used to model the biological structures listed on Master 1.1,
Searching for Scale. They should enter their results in columns 4, Assessment:
5, and 6 of the master. Allow 15 minutes for this activity.
Listening to student
responses will help
Students may approach this activity in different ways. Some may
you assess their under-
find it useful to determine the size of the object they are looking
standing of scale and
for first by multiplying the ratio in column 3 by 10 m. Some stu-
modeling. Collecting
dents may begin by locating objects, measuring them, and then
their completed tables
determining whether they meet the size requirements.
(Master 1.1, Search-
ing for Scale) allows
Teacher note: It is helpful to have objects available in the class-
a more formal oppor-
room that will meet the size requirements for modeling the bio-
tunity to evaluate stu-
logical structures in Master 1.1. Objects, such as erasers, marbles,
dents’ understanding.
49
Student Lesson 1
Using Technology to Study Cellular and Molecular Biology
fine- and ultrafine-tip pencils or pens, pieces of candy, an inflated
balloon, balls of different sizes, and other easily obtained materi-
als, ensure that students will be able to find something to serve as a
model for each structure.
12. Ask student pairs to share some of their results with the class.
Students should realize that the size ratios in columns 3 and 6 are
the same. In other words, modeling allows relative sizes to be stud-
ied, although the actual sizes of the real biological structure and its
model differ quite a bit.
Discussion Questions
1.
If a cell of 1 × 10–5 m (10 × 10–6 m, or 10 µm) diameter is repre-
sented by a room 10 m across, what distance would represent a
human 2 m tall?
First, as in column 3 of Master 1.1, Searching for Scale, derive the
relationship between the size of the human and the size of the cell:
2 meters ÷ (1 × 10–5 meter) = 2 × 105.
Thus, a 2-m-tall individual is 2 × 105 times larger than a cell
1 × 10–5 m in diameter.
If the cell is represented by a distance of 10 m, the 2-m-tall indi-
vidual would be represented by a distance of
10 m × (2 × 105) = 2 × 106 m (2,000 km, or 1,250 miles)
As a reference, this distance is the same as that from Boston to
Miami, Kansas City to Boston, or Los Angeles to Dallas. This cal-
culation is intended to provide a “wow” for the students, and they
derive an understanding of the difference in size between a human
and a molecule (in this example, the difference between
2,000,000 m for the human and 2 to 5 mm for a protein). This
should help students understand the need for specialized technolo-
gies for studying living systems at the cellular and molecular levels.
2.
As a lead-in to Lesson 2, write the following terms on the board
in random order: Eye; Light Microscopy; Electron Microscopy;
X-ray Techniques. Ask students to speculate on which technol-
ogy (or technologies) could provide useful information about the
objects on Master 1.1, Searching for Scale. What would make one
technology more useful than another in any given situation?
Students should realize that naked-eye observation is useful only
for relatively large objects and is not useful at all for discerning
cellular and subcellular objects. They also will realize that light
microscopy is useful for looking at cells and resolving some
50
organelles, like the nucleus and vacuoles. Students should know
from material in their texts that electron microscopy is used to pro-
vide details about cells and subcellular structures. Some may have
seen electron micrographs of DNA. Most students know little about
X-ray technologies, although they may have heard of X-ray crystal-
lography as a technique that was used to help resolve the structure
of DNA. If students have ideas about why certain technologies are
better for some tasks than others, write those responses on the
board. Indicate that the reason for having the right tool for the
right task is addressed in Lesson 2.
51
Student
Student L
L essons
esson 1
How Your
Using T Brain Understands
echnology to Study What Your
Cellular Ear
and Hears
Molecular Biology
Lesson 1 Organizer
Activity 1: Technology—What’s It All About?
What the Teacher Does
Procedure Reference
Ask students,
Pages 44–45
• “What is technology?”
Steps 1–2
• “In general, what does technology do for us?”
Focus discussion of technologies relevant to each student’s life.
Pages 45–46
• Ask students to look around the room; what technolo-
Steps 3–5
gies do they see?
• How do these technologies solve problems and make
their lives easier?
• Pick a technology mentioned. Ask students what types of
knowledge were required to develop that technology.
• After discussion, ask students to rethink and refine their
definition of technology.
Tell students to imagine that they live in the Stone Age. Their
Page 46
only garment is ripped and requires mending. Ask,
Steps 6–7
• “How would you mend the garment?”
• “How would your approach to mending the garment
change as time advanced from the Stone Age to the
present?”
• “What new knowledge would allow the development of
new technology?”
Write the words problem and technology on the board. Ask
Page 46
students to use arrows to draw a graphic that represents the
Step 8
relationship they believe exists between a problem and the
technology needed to solve it.
Activity 2: Searching for Scale
What the Teacher Does
Procedure Reference
Ask students,
Page 47
• “How do biological structures, such as cells, organelles,
Step 1
bacteria, and viruses, compare in size with one another?”
• “How do molecules compare in size with biological
structures such as cells, organelles, bacteria, and
viruses?”
52
Tell students that they will investigate the relative sizes of differ-
Pages 47–48
ent biological structures.
Steps 2–5
• Give each student a copy of Master 1.1, Searching for
Scale.
• Work with the class to complete column 3, Size relative
to cell.
• Ask students to define scale based on the information in
columns 2 and 3.
• Ask students if they can visualize the 100,000-fold
difference in size between a cell and a water molecule.
How could they demonstrate this large size difference?
• Ask two students to measure and mark approximately
Pages 48–49
10 m along both the length and width of the classroom.
Steps 6–7
• Tell students that the space defined by 10 m wide, 10 m
in length, and the height of the room is a model for a
typical
cell.
Organize students into pairs.
Pages 49–50
• Give each pair a ruler.
Steps 8–11
• Tell students that they will be searching the classroom
for objects that model the biological structures on Mas-
ter 1.1, Searching for Scale.
• Tell students to use the information provided in the last
three columns of Master 1.1 to help in their search.
• Instruct students to complete the last three columns of
Master 1.1 as they locate appropriate objects.
Ask students to share some of their results with the class.
Page 50
Step 12
= Involves copying a master.
53
Student Lesson 1
Lesson 2
Explore
Explain
Resolving Issues
Overview
At a Glance
This lesson consists of two activities linked by classroom discussion. In
the first activity, which is similar to the game Battleship, students inves-
tigate the concept of resolution and the relationship between probe size
and resolution. The second activity incorporates results from the first
activity and classroom observation and discussion. Students discover that
in order to understand the complete structure of an object, it is necessary