In this lesson, students are formed into groups of 5-7 and given string so they can connect themselves together to form a computer network. Students are given several specific networks to form, along with several guidelines for how to best form computer networks. Students are also forced to wrestle with conflicting guidelines in determining the 'best' way to connect together to form a network, and will need to justify why they chose the networks that they did.


Students will be able to:



The physical activity in this lesson helps provide a memorable experience and personal anchor for the rest of the unit - we can refer to the networks created in this activity to help motivate concepts in later lessons. In the final challenge for this lesson, it is important to let students wrestle with how to best balance the 3 network guidelines and refine their reasoning & explanation for decisions they made when creating their network. This is important in setting up later lessons in this unit - in this lesson, the guidelines are based on the physical impacts of creating a network but towards the end of the unit students will examine the societal and economical impacts for creating computer networks and will again think critically about how to balance several factors from a societal and economic lens.

Warm Up

Prompt: Often, we want to send messages to other people. Let's imagine that you want to send messages to a friend, so you set up a system where each of you were connected to each other by a single wire. What are the potential problems with this setup?

Discussion Goal: Direct the conversation towards the need to be able to talk to multiple people and the need to have a backup if that wire is damaged or unable to transmit information.



Group: Place students in groups of 5-7. Give each group string according to the following chart:

Teaching Tip: The number of strings per group is calculated by adding up all of the numbers less than the group size. For example, a group of 5 needs 4+3+2+1 = 10 strings. A group of 8 would need 7+6+5+4+3+2+1 = 28 strings.


Do This: Students should solve the challenges while following the given guidelines. Give them the first two guidelines before the first challenge. After each challenge, there is also a new guideline students need to follow for the next challenge. For each one, announce the challenge for students and give them a few minutes to form their network using the provided strings. These challenges progress in a specific way, with each guideline helping to motivate the next challenge.

Challenge #1

Challenge: As a group, create a network where everyone can speak directly to everyone else.

Challenge #2

Guideline #3: Strings cost money, so try to use the least number of strings possible.

Challenge: As a group, create a network that uses the least number of strings.

Challenge #3

Guideline #4: Strings can be cut, which might disconnect people from the network.

Challenge: As a group, create a network that keeps everyone connected even if any line is cut.

Challenge #4

Guideline #5: Direct connections are faster than long paths with indirect connections.

Challenge: As a group, create a network that you feel balances all 3 guidelines. There are many possible answers to this as long as you have a reason for why you created the network that you did.

Teaching Tip: The first 3 challenges have very direct solutions with most networks in the class looking nearly identical:

A diagram showing solutions for the first three challenges for a group of five arranged in a circle. The first solution uses a string between every pair of students. The second solution uses four strings, where the first student has a string to the second, the second has a string to the third, and so on. The third solution is identical to the second, except the last student also has a string to the first student, forming a loop.

Prompt: Thinking about our guidelines, what is a strength of the network your group created? What is a weakness for the network your group created?

Discussion Goal

There are many possible answers to Challenge 4 so its important for students to think critically about why they made the choices that they did. They can think of Challenge 1 and Challenge 2 as the two extremes - too well connected and not connected enough - and their network finds a balance somewhere in the middle.

You may choose to have groups draw their networks on a sheet of paper and write their responses along with their network drawing. This can help students process their thinking, and can act as an artifact for reference throughout the unit.


Wrap Up

Do This: Share these vocabulary words with their definitions (students do not write these down yet):

Discussion Goal: Students should discuss in pairs how to describe today's activity using the new vocabulary from this unit. They should make the following connections between these words and this activity:


Journal: Record the following words and definitions in your journal: Computing Device, Computing System, Computing Network, Path, Bandwidth.

Assessment: Check for Understanding

Question: Describe two different paths that a message could take from Person A to Person D:

A network diagram with five people, labeled A through E. A is connected to B and E. B is connected to A, C, and D. C is connected to B, D, and E. D is connected to B and C. E is connected to A and C.

Standards Alignment