Less Than Zero By Alex Sabatino
 3-5 One or two 45-minute  class periods
 In this lesson students examine negative numbers by extending a vertical number line to include numbers less than zero. To begin the lesson, students will start by playing a game using a die, two game pieces, and a game board. Starting at "0," players will move their game piece according to the roll of their die. Even numbers rolled move up, odd numbers down. The game ends when a player goes off the board in either direction. Students discover that some games can end after only one move. If the game board were extended to include numbers less than 0 (start), then games would be longer and more interesting. The class then examines a similar problem experienced by the Cyberchase team. The Cyberchase kids call the numbers less than 0 negative. Students will extend the Cyberchase problem to their own by extending their game boards to include positive, negative numbers and zero. Students will be able to: Extend a vertical number line to include negative numbers; Order numbers on the number line; Find the distance between numbers on a number line. From the National Council of Teachers of Mathematics Standards for grades K-12, available online at: http://www.nctm.org/standards/standards.htm Instructional programs from Pre-K through grade 12 should enable all students to: Understand numbers, ways of representing numbers, relationships among numbers, and number systems; Negative integers should be introduced at this level through the use of familiar models such as temperature or owing money. The number line is also an appropriate and helpful model, and students should recognize that points to the left of zero on the horizontal number line can be represented by numbers less than zero. Video: Cyberchase #121: Less Than Zero Web sites: Cyberchase: Space Coupe http://pbskids.org/cyberchase/games/negativenumbers/index.html An interactive activity on the PBS Kids Cyberchase site, this game applies student knowledge of positive and negative numbers by moving a space coupe up or down to destroy virus pods. Per Pair of Students: One die One ruler Two game pieces (pennies, markers, chips, etc.) One Game Board (see attached) One Game Rules and Score Sheet (see attached)