 The game here playing is called Back-to-Back. In this game, players think informally and algebraically as they solve linear equations to find a missing number when given a numerical expression orally. To get started, you will need to collect the following items to play. Calculator, two dry erase markers and erasers, two six-sided dice, tokens or bingo chips, two manila folders, two sheet protectors and scrap paper. Play in a group of three players. The player with the longest last name is the judge. The other two players sit close to each other. A wall is set up between players using manila folders or other materials so they cannot see each other's work. Players can write on page protectors using dry erase markers to save paper. The judge stands where numbers written by players one and two are visible to the judge. The object of the game is for the players to use informal reasoning to solve for the missing value in linear equation. Now let's play. First, the judge calls out numbers up two through nine. This signals players one and two to write a number of their choice from two through nine on their individual page protectors. The judge rolls two different colored dice. Each number rolled is multiplied by one player's number. For example, we see here that player one writes four. Player two writes six. The judge rolls the red die and multiplies a number on the red die by the number player one writes. The judge rolls the green die and multiplies a number on the green die by the number player two writes. The judge states one times player one's number plus six times player two's number is 40. The judge could also have used subtraction to give a result. Each player then solves for the opponent's mystery number. We see that player one solved the expression correctly first. This means player one won that round. This process is repeated for a total of three rounds while switching the role of the judge each round. The player who wins the most rounds wins the game. Here are some questions to think about while playing the game. How did you solve for your opponent's mystery number? Can you solve for your opponent's number more than one way? Try using pictures to solve for your opponent's mystery number. Are you able to form an equation at any step when finding the solution? Here are some ways to modify the game. To increase the challenge, the judge can choose two larger numbers to multiply the numbers chosen by players one and two. The judge may also use multiplication or division to combine the results of player one's and player two's numbers. If players have trouble solving equations, play a sample round and ask players to share how they think about solving for their opponent's mystery number. Find more thorough instructions using the link below. Thanks for playing!