This lesson consists of two activities linked by classroom discussion. Its purpose is to engage students in the general topic of technology. The first activity involves classroom discussion and a short scenario to allow students to develop a sense of what technology is and to dispel the notion that technology relates mostly to computers. The second activity introduces students to the concept of scale by using the classroom to repre-sent a cell and other smaller objects to represent subcellular components.
Technology is a body of knowledge used to create tools, develop skills, and extract or collect materials. It is also the application of science (the combination of the scientific method and material) to meet an objective or solve a problem. Scale is a way to represent the relationship between the actual size of an object and how that size is characterized, either numerically or visually.
After completing this lesson, students will
|Activity 2||Master 1.1, Searching for Scale, 1 copy per student|
|Activity 1||none needed|
No preparations needed.
No preparations needed.
Tip from the field test: Activities 1 and 2 can be conducted in several ways. You can engage the class as a whole in discussion as directed. Alternatively, you can divide the class into groups of three to five students each, ask each group to consider the questions you ask, and then have each group provide its responses. It is also possible to have student groups consider only a limited number of the questions and then handle the remainder with the whole class. If you choose either of the last two approaches, you should limit the time allotted for groups to consider each question to several minutes. Field-testing indicated that no approach was superior to another.
Accept all answers and write student responses on the board. Do not attempt to have students refine their definitions of technology at this point. They will revisit their definitions and refine them in Step 5. Students, like older individuals, may harbor the preconception that technology relates mostly to computers. Through advertisements and media articles, they are familiar with the terms information technology and computer technology.
Teacher note: Asking this question requires students to call on their prior knowledge, and it engages their thinking. At this point, do not critique student responses. Appropriate teacher comments are short and positive, such as “good” and “what else?” Other appropriate teacher responses include, “Why do you believe that?” or “How do you know that?” Questions such as these allow the teacher to assess students’ current knowledge about the subject and to adjust lessons accordingly. They also provide a springboard to “Let’s find out” or “Let’s investigate.” In general, it is time to move forward when the teacher sees that thinking has been engaged.
This question may help students understand that technology helps us solve problems, makes our lives easier, and extends our abilities to do things. Technology is used to develop skills or tools, both in our daily lives and in our occupations.
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 stereos, 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.
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, mathematics, chemistry, and computer science.
Students should mention that technology is a way of solving problems through the application of knowledge from multiple disciplines.
Students first should recognize that the ripped garment is a problem requiring a solution. They should consider what technologies they have available. The Stone Age was a period early in the development 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.
Student responses will vary, and some students may want to jump directly from the Stone Age to the modern sewing machine. Slow them down and have them consider incremental changes in knowledge and technologies. They may cite the use of metals to fashion repair tools, like knives and finer needles. New knowledge of metals and chemistry would help here. Later advances in engineering 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 engineering 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 clothing), advances in technology change how the problem is solved.
They can use arrows of any kind, and they should be prepared to defend their suggestions. The graphic should illustrate that a problem does not drive technology unidirectionally, nor does technology 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:
Accept all responses and write them on the board. Students will explore these size relationships in the next steps.
The table with column 3 completed is as follows:
Relative to Cell
|Object Used to Model
|Measured Size of
|Size Relative to
Model Cell (the Room)
|Glucose molecule||0.1 cm
|H2O molecule||0.1 mm|
Accept all answers and write them on the board. Guide discussion so that students realize that scale is a way to represent the relationship between the actual size of an object (for example, its length or mass) and how that size is characterized either numerically or visually. 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.
Master 1.1, Searching for Scale, provides the necessary clues for students, since the heading of column 4 is Object used to model biological 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.
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.
Explain that they will be looking for objects that have the same size relative to the model cell (the room) that the actual biological structure has to a real cell.
Students may approach this activity in different ways. Some may find it useful to determine the size of the object they are looking for first by multiplying the ratio in column 3 by 10 m. Some students may begin by locating objects, measuring them, and then determining whether they meet the size requirements.
Teacher note: It is helpful to have objects available in the classroom that will meet the size requirements for modeling the biological structures in Master 1.1. Objects, such as erasers, marbles, fine- and ultrafine-tip pencils or pens, pieces of candy, an inflated balloon, balls of different sizes, and other easily obtained materials, ensure that students will be able to find something to serve as a model for each structure.
Students should realize that the size ratios in columns 3 and 6 are the same. In other words, modeling allows relative sizes to be studied, although the actual sizes of the real biological structure and its model differ quite a bit.
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 individual 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 calculation 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 technologies for studying living systems at the cellular and molecular levels.
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 organelles, like the nucleus and vacuoles. Students should know from material in their texts that electron microscopy is used to provide 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 crystallography 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.
|Activity 1: Technology—What’s It All About?|
|What the Teacher Does||Procedure Reference|
Focus discussion of technologies relevant to each student’s life.
Tell students to imagine that they live in the Stone Age. Their only garment is ripped and requires mending. Ask,
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 technology needed to solve it.
|Activity 2: Searching for Scale|
|What the Teacher Does||Procedure Reference|
Tell students that they will investigate the relative sizes of different biological structures.
Organize students into pairs.
Ask students to share some of their results with the class.
|= Involves copying a master.|