INSTRUCTOR’S GUIDE & PYTHON LAB
COMPUTER SCIENCE: AN OVERVIEW
13TH EDITION
CHAPTER ZERO: INTRODUCTION
Chapter Summary
This chapter introduces computer science as the discipline that seeks a scientific foundation for
topics such as computer design, computer programming, algorithmic processes, etc. It gives an
informal introduction to the concept of an algorithm (more detail is given in Chapter 5) and
discusses how this concept forms the foundation of the field known as computer science. The
chapter also presents a brief history of computing machinery and introduces the “Big Ideas of
Computer Science” of the College Boards codification, namely; algorithms, abstraction, creativity,
data, programming, Internet, and impact. These can be found in “The Principles Project”, by Owen
Astrachan and Amy Briggs, a publication on the CS Principles website (www.csprinciples.org).
A major goal of this chapter is to establish the concept of computer science as being the
underpinning for the development of the computer applications with which students are familiar.
Most introductory students will have seen computer science only in the context of using application
software, Web browsing, and perhaps some programming. Thus, they may not understand the
distinction between studying computer science and learning how to use today’s computer
application software. I find it helpful to explain that computer science deals with the development
of tomorrow’s application software, rather than learning how to use the applications of today.
Comments Comments
1. This introductory chapter is included to set the stage for the course, and is your chance to tell
your students the answer to the question “What is Computer Science all about?” You may choose to
answer this question in any number of ways. You could, for instance, discuss the branches of
study that your institution considers essential for a major. Another possibility is to explain to
students how Computer Science is different from merely teaching “coding.”
2. The Overarching Themes of Computer Science (creativity, abstraction, data, algorithms,
programming, Internet, and impact) in Section 0.4 provide a chance for you as an instructor to
bring your student’s prior knowledge into the study of the course. For instance, you could ask your
,students to consider how each of the seven overarching themes of computer science is embodied in
Facebook. Abstraction can be a difficult concept for students to grasp, so it would help for you to
give a specific definition as well as some examples.
3. The topics discussed throughout the text collectively provide an understanding of computer
science. There is probably no single topic that a student must know. (Do students really have to
know about error correcting codes, two's complement arithmetic, or the significance of the halting
problem?) So don't hesitate to skip a topic if it doesn't fit your course goals. On the other hand, I
encourage you to cover a wide range of topics. The goal is to introduce students to computer
science by presenting a variety of topics in enough detail to expose the realities of the issues
involved. (Each individual topic may not be necessary on its own, but together they paint an
important picture.)
Maintaining this perspective is perhaps more of a challenge when teaching a computer literacy
course than a course within a computer science curriculum. In these former cases there is a
temptation to skip the more challenging or tedious topics since "they don't need to know that
anyway." In contrast, I prefer to go ahead and present such subjects in a manner compatible with
the audience and then adjust the level of assignments and exams to match the objectives of the
particular course and the abilities of the students.
4. Each chapter will end with “Social Issues” questions. If your course has a discussion section,
these questions would best be discussed in that environment. Alternatives would include a weekly
online class discussion, in which each student must post one unique perspective, and must
comment on at least 2 other students posts.
CHAPTER NO. 01: DATA STORAGE
Chapter Summary
This chapter presents the rudiments of data storage within digital computers. It introduces the
basics of digital circuitry and how a simple flip-flop can be used to store a single bit. It then
discusses addressable memory cells and mass storage systems (magnetic disk, compact disks, and
flash memory). Having established this background, the chapter discusses how information (text,
numeric values, images, and sound) are encoded as bit patterns and lays a foundation for the binary
system. The optional sections in this chapter are not required for subsequent material in the text.
However, these topics are relevant to Computer Science Principles and answer some common
questions that students have about binary representation of information.
,Comments
1. This chapter could really be thought of as four separate chapters, covering the topics of
Representation of Information as Bits, Storage of Bits in Memory with Logic Gates, Compression
and Transmission of Bits, and Programming in Python. In a 15-week course, you may find that this
material takes 2-3 full weeks, and in a high school course, this material may take 4-6 weeks.
Although the Python component of the chapter is one section, students respond well to a regular,
small amount of programming each week.
2. The material in section 1.1 often overwhelms students who have never seen it before. I prefer to
start this chapter, with sections 1.4 (Representing Information as Bit Patterns) and 1.5 (The Binary
System). I would then move through the remaining sections in order: 1.1, 1.2, 1.3, 1.6, 1.7, ….
3. Section 1.1 needs careful, and slow, explanations. It may help to give students extra examples of
logic gates and combinations of logic gates before a Flip-Flop is introduced. One of the Student
Activities for this chapter helps build this foundation. The textbook places the process for building
adders using logic gates in Appendix B, but I have found it is worth the time to discuss adders in
lecture.
4. While storing integers (1.6) and fractions (1.7) are complicated processes, they answer questions
that students should have after reading section 1.5, namely, “How do computers represent negative
numbers?” and “How do computers represent numbers in Scientific Notation?” Some students may
find these sections difficult.
5. As mentioned above, the Python sections could be taught in little parts that occur regularly
throughout the course. Decide ahead of time how you will support your students in setting up an
IDE to use Python. Several free, cloud-based Python systems have been developed. I prefer these
environments to those that must be installed on a machine, and I encourage my students to use
them.
6. The sections on data compression and communication errors allow students a chance to act out
some algorithms by hand. It can also reinforce the earlier ideas of the chapter. While these topics
are not needed for future chapters, I find it gives students a taste of what computer scientists do.
It’s important for students to understand that computers have practical limitations, but that
computer scientists have developed ways to work around these limitations.
, ANSWERS TO CHAPTER REVIEW PROBLEMS
1. With a 1 on the upper input and a 0 on the lower input, all circuits will produce an output 0. If instead a 0
is on the upper input and 1 is on the lower input, circuits b and c will produce an output 1, and circuit a will
still produce a 0.
2. a. The entire circuit is equivalent to a single AND gate.
b. The entire circuit is equivalent to an Exclusive OR gate.
3. a. After the third pulse, this circuit will produce an output of 1 and 1. After the fourth pulse, both flip-flops
are flipped back to a 0 state so the circuit will again produce an output of 0 and 0. It is interesting to note
that this circuitry forms a binary counter that will repeatedly count from 00 to 11. Thus, this circuit forms
an abstract tool that can be used as a building block in other circuits. Additional flip-flops can be added
to count through a larger range of numbers.
b. A 1 will be sent on Output B on the 2nd, 6th, 10th … pulses of the clock. Likewise, a 1 will be sent to
Output C on the 3rd, 7th, 11th … pulses of the clock. A 1 will not be sent to any output on the 4th, 8th, 12th
… pulses of the clock. As we move forward into the next chapter, a circuit similar to this can be used to
drive the machine cycle (composed of fetch, decode, and execute). Output A would be connected to the
input that activates the fetch circuitry. Likewise Output B and Output C would be connected to the
decode and execute circuits respectively.
4. This is a flip-flop that is triggered by 0s rather than 1s. That is, temporarily changing the upper
input to 0 will establish an output of 1, whereas temporarily changing the lower input to 0 will
establish an output of 0. To obtain an equivalent circuit using NAND gates, simply replace each
AND-NOT gate pair with a NAND gate.
5. Address Contents
00 02
01 53
02 01
03 53
6. 256 using two hexadecimal digits (16 bits) , 65536 using four hexadecimal digits (32 bits).
7. a. 11001101 b. 01100111 c. 10011010 d. 11111111 e. 00010000
8. a. 1 b. 1 c. 0 d. 0
9. a. A0A b. C7B c. 0BE
COMPUTER SCIENCE: AN OVERVIEW
13TH EDITION
CHAPTER ZERO: INTRODUCTION
Chapter Summary
This chapter introduces computer science as the discipline that seeks a scientific foundation for
topics such as computer design, computer programming, algorithmic processes, etc. It gives an
informal introduction to the concept of an algorithm (more detail is given in Chapter 5) and
discusses how this concept forms the foundation of the field known as computer science. The
chapter also presents a brief history of computing machinery and introduces the “Big Ideas of
Computer Science” of the College Boards codification, namely; algorithms, abstraction, creativity,
data, programming, Internet, and impact. These can be found in “The Principles Project”, by Owen
Astrachan and Amy Briggs, a publication on the CS Principles website (www.csprinciples.org).
A major goal of this chapter is to establish the concept of computer science as being the
underpinning for the development of the computer applications with which students are familiar.
Most introductory students will have seen computer science only in the context of using application
software, Web browsing, and perhaps some programming. Thus, they may not understand the
distinction between studying computer science and learning how to use today’s computer
application software. I find it helpful to explain that computer science deals with the development
of tomorrow’s application software, rather than learning how to use the applications of today.
Comments Comments
1. This introductory chapter is included to set the stage for the course, and is your chance to tell
your students the answer to the question “What is Computer Science all about?” You may choose to
answer this question in any number of ways. You could, for instance, discuss the branches of
study that your institution considers essential for a major. Another possibility is to explain to
students how Computer Science is different from merely teaching “coding.”
2. The Overarching Themes of Computer Science (creativity, abstraction, data, algorithms,
programming, Internet, and impact) in Section 0.4 provide a chance for you as an instructor to
bring your student’s prior knowledge into the study of the course. For instance, you could ask your
,students to consider how each of the seven overarching themes of computer science is embodied in
Facebook. Abstraction can be a difficult concept for students to grasp, so it would help for you to
give a specific definition as well as some examples.
3. The topics discussed throughout the text collectively provide an understanding of computer
science. There is probably no single topic that a student must know. (Do students really have to
know about error correcting codes, two's complement arithmetic, or the significance of the halting
problem?) So don't hesitate to skip a topic if it doesn't fit your course goals. On the other hand, I
encourage you to cover a wide range of topics. The goal is to introduce students to computer
science by presenting a variety of topics in enough detail to expose the realities of the issues
involved. (Each individual topic may not be necessary on its own, but together they paint an
important picture.)
Maintaining this perspective is perhaps more of a challenge when teaching a computer literacy
course than a course within a computer science curriculum. In these former cases there is a
temptation to skip the more challenging or tedious topics since "they don't need to know that
anyway." In contrast, I prefer to go ahead and present such subjects in a manner compatible with
the audience and then adjust the level of assignments and exams to match the objectives of the
particular course and the abilities of the students.
4. Each chapter will end with “Social Issues” questions. If your course has a discussion section,
these questions would best be discussed in that environment. Alternatives would include a weekly
online class discussion, in which each student must post one unique perspective, and must
comment on at least 2 other students posts.
CHAPTER NO. 01: DATA STORAGE
Chapter Summary
This chapter presents the rudiments of data storage within digital computers. It introduces the
basics of digital circuitry and how a simple flip-flop can be used to store a single bit. It then
discusses addressable memory cells and mass storage systems (magnetic disk, compact disks, and
flash memory). Having established this background, the chapter discusses how information (text,
numeric values, images, and sound) are encoded as bit patterns and lays a foundation for the binary
system. The optional sections in this chapter are not required for subsequent material in the text.
However, these topics are relevant to Computer Science Principles and answer some common
questions that students have about binary representation of information.
,Comments
1. This chapter could really be thought of as four separate chapters, covering the topics of
Representation of Information as Bits, Storage of Bits in Memory with Logic Gates, Compression
and Transmission of Bits, and Programming in Python. In a 15-week course, you may find that this
material takes 2-3 full weeks, and in a high school course, this material may take 4-6 weeks.
Although the Python component of the chapter is one section, students respond well to a regular,
small amount of programming each week.
2. The material in section 1.1 often overwhelms students who have never seen it before. I prefer to
start this chapter, with sections 1.4 (Representing Information as Bit Patterns) and 1.5 (The Binary
System). I would then move through the remaining sections in order: 1.1, 1.2, 1.3, 1.6, 1.7, ….
3. Section 1.1 needs careful, and slow, explanations. It may help to give students extra examples of
logic gates and combinations of logic gates before a Flip-Flop is introduced. One of the Student
Activities for this chapter helps build this foundation. The textbook places the process for building
adders using logic gates in Appendix B, but I have found it is worth the time to discuss adders in
lecture.
4. While storing integers (1.6) and fractions (1.7) are complicated processes, they answer questions
that students should have after reading section 1.5, namely, “How do computers represent negative
numbers?” and “How do computers represent numbers in Scientific Notation?” Some students may
find these sections difficult.
5. As mentioned above, the Python sections could be taught in little parts that occur regularly
throughout the course. Decide ahead of time how you will support your students in setting up an
IDE to use Python. Several free, cloud-based Python systems have been developed. I prefer these
environments to those that must be installed on a machine, and I encourage my students to use
them.
6. The sections on data compression and communication errors allow students a chance to act out
some algorithms by hand. It can also reinforce the earlier ideas of the chapter. While these topics
are not needed for future chapters, I find it gives students a taste of what computer scientists do.
It’s important for students to understand that computers have practical limitations, but that
computer scientists have developed ways to work around these limitations.
, ANSWERS TO CHAPTER REVIEW PROBLEMS
1. With a 1 on the upper input and a 0 on the lower input, all circuits will produce an output 0. If instead a 0
is on the upper input and 1 is on the lower input, circuits b and c will produce an output 1, and circuit a will
still produce a 0.
2. a. The entire circuit is equivalent to a single AND gate.
b. The entire circuit is equivalent to an Exclusive OR gate.
3. a. After the third pulse, this circuit will produce an output of 1 and 1. After the fourth pulse, both flip-flops
are flipped back to a 0 state so the circuit will again produce an output of 0 and 0. It is interesting to note
that this circuitry forms a binary counter that will repeatedly count from 00 to 11. Thus, this circuit forms
an abstract tool that can be used as a building block in other circuits. Additional flip-flops can be added
to count through a larger range of numbers.
b. A 1 will be sent on Output B on the 2nd, 6th, 10th … pulses of the clock. Likewise, a 1 will be sent to
Output C on the 3rd, 7th, 11th … pulses of the clock. A 1 will not be sent to any output on the 4th, 8th, 12th
… pulses of the clock. As we move forward into the next chapter, a circuit similar to this can be used to
drive the machine cycle (composed of fetch, decode, and execute). Output A would be connected to the
input that activates the fetch circuitry. Likewise Output B and Output C would be connected to the
decode and execute circuits respectively.
4. This is a flip-flop that is triggered by 0s rather than 1s. That is, temporarily changing the upper
input to 0 will establish an output of 1, whereas temporarily changing the lower input to 0 will
establish an output of 0. To obtain an equivalent circuit using NAND gates, simply replace each
AND-NOT gate pair with a NAND gate.
5. Address Contents
00 02
01 53
02 01
03 53
6. 256 using two hexadecimal digits (16 bits) , 65536 using four hexadecimal digits (32 bits).
7. a. 11001101 b. 01100111 c. 10011010 d. 11111111 e. 00010000
8. a. 1 b. 1 c. 0 d. 0
9. a. A0A b. C7B c. 0BE
