In this lesson student develop a protocol for reliably sending a message over an unreliable internet. The Internet Simulator has been setup for this lesson to restrict messages to no more than 8 characters each, and messages get dropped messages with some probability on every hop.

Students are given time to experiment with the Internet Simulator and develop their own protocol, possibly testing or demonstrating their protocol to their peers. At the conclusion of the lesson, students watch a short video explaining how these challenges are addressed in the real world with [v TCP] - the Transmission Control Protocol.

The core idea of this lesson occurs in the unplugged activity that kicks off the lesson, in which students try to keep track of IP addresses that had been randomly assigned to each student in the class, while at the same time the teacher occasionally changes students' addresses. This leads to identifying the need for an authoritative system for name-to-address mappings, known as the Domain Name System or [v DNS].

Students then briefly experiment with a DNS protocol in the Internet Simulator. The activity is similar, in that students will have to grapple with IP addresses changing in real time and use the built in DNS protocol to resolve the issues.

The lesson ends with students doing some rapid research about DNS and some of its vulnerabilities, particularly what are known as Denial of Service Attacks.

Students are introduced to the Internet Simulator, a tool they will return to many times in the first two units of the course. Today, the Internet Simulator will be used to simulate a single shared wire, connecting two people. The wire can only be in one of two possible states (state A or state B) and either partner may set or read the state of the wire at any time, but this is the only way in which students may communicate. Students must invent a binary call-response [v protocol] using this system. Coordination, speed and timing are problems that need to be solved. At the conclusion of the lesson, students compete to demonstrate the speed and accuracy of their protocols, and calculate the [v bit rate] of their message exchange.

In this lesson students will return to the Internet Simulator in order to send a simple line drawing to a classmate. Students will be presented a grid on which they will draw an image (connecting 3-7 dots with straight lines). They must develop a protocol which will allow them to send any image they might create on their grids, paying particular attention to how many bits are used to represent each binary number. Students will therefore have additional practice encoding and decoding binary numbers and develop further intuitions about the properties of binary numbers in a hands-on way. The lesson concludes by testing protocols using a teacher-supplied test-image to transmit.

In this lesson, students create their own system for representing text in binary and explore how their newfound ability to convert between binary and decimal numbers helps in this process. In the warm up students quickly create a system for representing the 50 states in binary. They then move to the main activity where they create a system for representing text using only numbers while communicating on the Internet Simulator. At the end of the main activity they briefly review the ASCII system. The wrap up discussion introduces the concept of abstraction and its connection to the chapter. Following this lesson there is a chapter assessment that reviews the contents of this and the previous lessons.

In this lesson, students explore more deeply how communication between multiple computers can work over the Internet. They do this by playing a simplified game of Battleship, in which the first game is played unplugged, in their table groups, and the second game is played using the Internet Simulator, so that multiple students can connect to each other and see each other’s messages. Students must devise a messaging protocol that makes it clear who is sending the message and who the intended recipient is.

Students then devise a *binary protocol* for playing this game which will entail developing an addressing system for players, as a well as a formal packet structure for transmitting data about the state of the game.

**NOTE**: this is a large lesson that will likely need to span 2 days of class.

These strategies support active student participation in math lessons and allow teachers to assess the developing proficiency levels of all students in the class by walking around to monitor student responses. These strategies are especially effective during the Mental Math part of an Everyday Mathematics lesson.

Interactive learning is becoming increasingly important as the world and its demands continue to change. This approach to education provides many advantages for both students and educators. By promoting engagement, supporting collaboration, personalizing learning experiences, utilizing technology, and developing critical thinking skills, this educational method equips students with the necessary tools to succeed in the 21st-century workforce. Please email me at interactivelearning2288@gmail.com to receive a copy of my book that contains all 14 units. Please allow me several days to respond.

Students use a hundred board to eliminate numbers after reading each clue. Students must apply their knowledge of even-odd, multiples and place value to successfully eliminate numbers until the solution is revealed.