Lesson 1 (Beta)

The Security Mindset:

Cybersecurity through Threat Modeling

About This Lesson:

Lesson 1 introduces students to the basic concepts of cybersecurity and the “Security Mindset”. This perspective frames the topics in the remaining lessons.

Intended Audience: High school students or early undergraduates. Geared towards AP Computer Science Principles, but compatible with any introductory computer science course.

Delivery Format: Traditional classroom.

Duration for Whole Unit: 75 minutes (with options to shorten or lengthen).

Learning Objectives
After completing this lesson:

  1. Students can explain what cybersecurity is.
  2. Students can enumerate some reasons cybersecurity is important.
  3. Students can discuss some of the unique challenges in the field of cybersecurity that differentiate it from other design and engineering efforts.
  4. Students can identify the goals and summarize the overall process of threat modeling.
  5. Given a description of a system, students can predict and prioritize some potential threats (who might attack it and how) and the human impacts of those threats.

“Engage” Activities:

Introduce the topic, probe prior knowledge, and ignite students’ interest. (Choose one Engage activity, or use more if you have time.)

Quick Opening Questions (Whole-Class Mini-Discussion)

Estimated Time: 5-7 minutes.

What You’ll Need: Blackboard/whiteboard (optional).

Ignite Question

Are there any computer systems in the world that are safe from being hacked? Why or why not?

Optional Follow-Up Prompt:

  • What would a totally safe system look like?

Target Answer + Details: No system is safe from attack. For a computer/system to actually be useful, it has to have some way for information to go in and come out (whether or not it’s connected to the Internet). It’s impossible to think of and protect against every way someone could possibly abuse those channels, other than just disabling them entirely.

Quick Knowledge Check

What is cybersecurity? What have you heard about it?

Optional Follow-Up Prompts:

  • In what ways is it important?
  • Who is it important to?
  • Why do you need to protect systems from attackers? Who would do such a thing and why?

Target Answer + Details:

  • Cybersecurity is about studying and protecting computer systems from adversaries who attempt to use the system in a way that it wasn’t meant to be used. (Where “computer systems” include many kinds of networked — or non-networked — devices, from smartphones to traffic lights.)
  • It’s important because any system that’s designed for whatever purpose can be misused by an attacker/adversary. In other words, it’s important to anyone who interacts with computer systems, which is pretty much everybody!
  • It’s common for criminals to attack a system for financial gain, i.e., to make money. It’s common for people to attack a system to exercise or demonstrate power, to prevent the real users from accessing the system, or simply because they’re bored or want to prove they can.
Small-Group Brainstorming Activity: Defend and Attack

Estimated Time: 5-10 minutes.

What You’ll Need: Print or write out slips of paper with a “secret” written on each one. Print one secret for each Blue Team, for them to keep hidden from the Red Team. Examples:

  • “[Teacher] likes [title of movie/book/etc.].”
  • “[Rival school]’s mascot is [name].”
  • A random number
  • An inspirational quote or a silly phrase

Description: In this activity, students get a taste of how cybersecurity involves thinking about possible attacks — but also experience the drawbacks of not using a structured approach to that thought process. This activity works best as a lead-in/contrast to the more organized activities later in this lesson plan.

Running the Activity:

  1. Ask your students to form groups of three or four. There should be an even number of groups overall.
  2. Introduce the concept of a Red Team/Blue Team exercise:
    • Red Team/Blue Team exercises take their name from a military exercise. The idea is simple: One group of security pros — a red team — attacks something, and an opposing group — the blue team — defends it.
    • In the physical world, these exercises are used by the military to test force-readiness. They are also used to test the physical security of sensitive sites like nuclear facilities and government labs that conduct top-secret research.
    • In the 1990s, cybersecurity experts began using Red Team/Blue Team exercises to test the security of information systems.

  3. Label each group as a Red Team or a Blue Team.
  4. Give each Blue Team a slip of paper with their “secret”.
  5. Tell the Blue Teams their task is to figure out a plan for protecting the information on the paper.
  6. Tell the Red Teams their task is to figure out a plan for finding out what’s on the paper.
    • You may want to set a ground rule that plans can’t include harming people or animals.
  7. Give the teams 3-5 minutes to discuss their ideas for protecting or obtaining the information.
  8. Beginning with one of the Red Teams, ask the groups to report back. After hearing a Red Team plan to get the paper, ask if any of the Blue Teams has a plan to prevent that specific attack. (Repeat a few times.)

Types of Plans You’re Likely to Hear:

  • Red Teams’ ideas will likely sort into two broad categories:
    • Direct attacks: Plans that rely on directly pursuing the secret or attempting brute force; and
    • Indirect attacks: Plans that rely on tricking the people involved into breaking protocol or exposing vulnerabilities.
  • Blue Teams may attempt to reduce their risk of direct or indirect attacks.

Higher-Level Ideas That May Emerge:

  • It’s tough to cover every possible attack.
  • It’s easier to think of attacks than it is to think of protection measures.
  • Brainstorming attacks and protections feels disorganized.
  • Both sides may have lots of open questions about what’s possible, or answers that begin with “It depends”.

Computing in the News - Cybersecurity Edition

Estimated Time: 3-7 minutes.

What You’ll Need: Computer and projector (optional).

Description: Teachers can use current news items about cyberattacks/data breaches or cybersecurity innovations to grab students’ attention at the beginning of class and illustrate the relevance of cybersecurity.

View Outline: “Computing in the News – Cybersecurity Edition”

“Explore” Activities:

Ground students’ learning in firsthand experience and spark new ideas.

Small-Group Activity: Threat Model a House

Estimated Time: 20-30 minutes.

What You’ll Need:

  • A whiteboard or a computer and projector
  • Copies of the worksheet (1 per group)
  • Students will need extra paper and pens/pencils

Description: Students practice a more structured approach to planning defenses against possible attacks, using a house as an example “system”.

Download Worksheet: “House Model Worksheet”

Running the Activity:

Introduction (2 minutes)

  1. Ask your students to form groups of 3-4.
  2. Introduce the activity:

    • We’re going to talk about a process that can be used to approach thinking about security. It’s called threat modeling.
    • At a high level, in threat modeling, you consider questions like what are you building or protecting, and what could go wrong?
    • In groups, we’ll work through an example of how you would create a threat model for a basic house.

Blue Team Portion (10-15 minutes)

  1. Pass out pages 1 and 2 of the worksheet to each group
  2. Explain:

    • In this activity, every group will start out as a Blue Team.
    • The house on the worksheet and your answers to the first couple of questions are the “model” of what you’re protecting. This is an abstraction of the system at the heart of your threat model.
    • The rest of the Blue Team questions involve thinking of ways that someone might attack the house or gain unauthorized access to the things inside.
    • Write detailed notes for the whole group on one copy of the worksheet. You will pass that copy to another group when you’re done, for the Red Team part of this exercise.
  3. Give students 10-15 minutes to complete the Blue Team part of the worksheet (i.e. pages 1-2).

Red Team Portion (5 – 10 minutes)

  1. Have groups swap worksheets (pages 1-2) and pass out page 3.
  2. Give students 5-10 minutes to plan how they could gain access to the valuables inside the houses.
    • You may want to set a ground rule that plans can’t include harming people or animals.
    • If you’re short on time, you can direct Red Teams to write their responses on page 3, but skip having them represent their attacks on the Blue Teams’ diagrams.

Debrief/Wrap-Up (3-10 minutes)

  1. Have students return the worksheets to the original group so each Blue Team can spend a couple of minutes review the attacking Red Team’s plans.
  2. Optional: Ask each group to share an example of a clever or unexpected Red Team attack against their house, or one that would be difficult to prevent. (I.E., they should share examples thunk up by the group attacking them, not their own attack on someone else.)
  3. Wrap up by highlighting how designing a secure system differs from other fields of engineering, in that you have an active, motivated adversary to contend with. That’s why cybersecurity is often called an arms race. And it’s just a fact that you cannot predict or prevent all attacks.


  1. Allow both teams’ imaginations to run wild.
  2. Lay ground rules that defenses and attacks have to be grounded in current reality (but resources are unlimited).
  3. Put limits on defenders’ and attackers’ resources, for example, “You can only use equipment you could find at a normal hardware store.”
  4. Allow students to assume unlimited resources during the main part of the activity, but ask them at the end to revisit their Blue Team plans and think about how the plans would have been different if their resources had been limited (for example, to normal hardware-store equipment).

“Explain” Activities:

Introduce important facts and underlying concepts.

Slide Deck: Cybersecurity and Threat Modeling

Estimated Time: 15 minutes.
What You’ll Need: Computer, projector, and speakers.

Description: In this presentation, students learn about what cybersecurity is, how threat modeling works, and why threat modeling is a useful place to start for cybersecurity. The slides are accompanied by Notes with details and examples to guide your lecture.

Access Slide Deck: “Cybersecurity and Threat Modeling”


  • Presents an overview of web security (4-minute video), slide 2
  • Defines cybersecurity, slides 3–9
  • Defines cyber attack, slide 10
  • Defines threat modeling, slides 11–14
  • Explains the strengths and limitations of threat modeling, slides 15–24

Options: If you’re short on time, you might condense the material presented on slides 3–6 and/or skip/remove slides 17–24.

Coming Soon: Graphic organizer for student note-taking.

“Elaborate” Activities:

Go deeper into the underlying concepts and/or let students practice important cybersecurity skills.

Small-Group Activity: Threat Modeling with the Security Cards

Estimated Time: 20-30 minutes
What You’ll Need:

  • Several sets of Security Cards (1 set per group)
  • “Suggested Systems” handouts (1 system/page per group) or students’ sketches of systems they’re already studying or building (if they already have sketches) or blank paper for students to sketch the systems they’re studying or building
  • Computer and projector

Description: Students use the Security Cards (from University of Washington) as a tool to practice threat modeling for a computer system. Includes a slide deck for introducing the activity.

Get Card Decks or Printable PDFs: The Security Cards from University of Washington
  • Educators can get free pre-printed decks; let them know where you heard about it. You can also print them yourself from a PDF.
Access Slide Deck: “Threat Modeling with the Security Cards” (Continues from Explain deck.)
Download Worksheet: “Suggested Systems”
  • The handout has four pages, one for each system. If you are using this option, assign one system to each group.

Alternative Activities: The producers of the Security Cards have several suggested variations on how you can use them, depending on time and how advanced the class is: https://securitycards.cs.washington.edu/activities.html

Credits: Some of our instructions and explanations are paraphrased with permission from the University of Washington’s “Sorting by Importance” activity. Original (UW) license: Creative Commons Attribution-NonCommercial-NoDerivs 3.0 (CC BY-NC-ND 3.0).

Coming Soon: Unplugged version with “Introducing the Security Cards” handout and slide-free teacher’s notes.

“Evaluate” Activities:

Assess students’ understanding of the material and development of new skills.

More for Teachers

Resources and background information to help you brush up on the technical nitty-gritty and be prepared for student questions.