Are you familiar with a game called **Shut the Box?**

Before last year, I never knew this game existed. Now that I do, I want to shout about it from the rooftops.

Shut the Box provides an excellent way to help children build their fluency with addition facts, and I think more teachers should have it in their repertoire.

Shut the Box involves a game board and two dice. The standard game board has nine numerals on it. There are plenty of videos that can be found on the internet to explain the rules of the game, and I encourage you to watch a few of them to get the basic idea. Single or multiplayer game boards can be purchased from various sellers or created using materials that are already available in many classrooms.

To start the game, all nine numerals are displayed. The player rolls the two dice. The player then flips over a number or combination of numbers corresponding to the sum of the two numbers displayed on the dice. Players can flip the two numerals corresponding directly to the number of pips displayed on the two dice, they can flip a single numeral corresponding to the sum, or they can flip any other combination of two or more numerals that add to the number of pips showing on the dice. The player keeps rolling the dice until all the numbers have been flipped or until they roll a combination of dice that cannot be made from the remaining numbers that have not yet been flipped. The player’s turn then ends, and their score is determined by the sum of all the numbers that were not flipped. As in golf, the lowest score wins. If a player manages to flip all nine of the numerals, they have “shut the box.” It is somewhat rare to shut the box, and it is always exciting when it happens.

There are many variations of the rules (and names) for the game. Some game boards have 12 numbers, not just 9. A common variation on the rules with the 12- number game is to also allow multiplication of the two quantities shown on the dice. There may also be variations of the rules that could incorporate subtraction. My fourth-grade daughter and I have adjusted the rules to enable multiplication or subtraction, but we usually revert back to the addition-only version.

In my family, we like to play a variation of the game involving multiple rounds. The game ends after a round when one of the players has a total score greater than 45. This variation creates reasons to practice performing the addition operation on multidigit numbers. The task of keeping score across multiple rounds can be assigned to a player who is ready for the challenge of performing that task. If a player shuts the box during any round, they automatically win the game, adding to the excitement of this phenomenon and the importance of developing strategy to maximize the likelihood of being able to shut the box.

Playing Shut the Box can improve fact fluency in various ways. At the simplest level, the game involves lots of practice with addition facts. It can be played solo or in groups. When it is played in groups, the opponents will naturally monitor and check the accuracy of their opponents, so it creates a natural way for the player to get feedback on their arithmetic. The element of randomness—introduced and supported by the dice—builds some suspense and keeps the game fun, so it doesn’t feel like just plain old drill and practice. To win the game, players will need to think flexibly about different ways that two (or more) numbers can be added. For example, if a player rolls a 5 and a 2, they could flip the 5 and the 2, or they could flip the 7. They could also flip the 4 and the 3, or they could flip the 6 and the 1. They could even flip the 1, 2, and 4. In this way, shut-the-box players are rewarded for thinking about relations among numbers and the addition operations and the various combinations of numbers that have the same sum. This flexible thinking relational understanding is an important component of fact fluency.

Another aspect that I like about this game is that it is accessible for players at different levels of mathematical sophistication. A person who is just learning how to count the pips on the dice and identify the numerals that correspond to the number of pips can play the game. The game can support early learners in developing their ability to subitize. At a more abstract level, players are practicing to evaluate sums of two numbers, and they are rewarded for thinking about various combinations of numbers that will yield a given sum. Even more sophisticated players will think strategically about which numbers to flip under certain conditions and the probability of various sums when the two addends are whole numbers between 1 and 6.

I hope you take a few minutes to learn and play Shut the Box. There is so much more to say about this game, and I hope you will use the comments feature in this blog to share your thoughts on the topic. If you find a good video that provides a good explanation for how to play the game, post a link to it in the comments. If you are playing the game with your students, tell us about your experiences and how you use the game in your classroom. If you find a good variation on the rules of the game, use the comments section to tell us about it.

In an attempt to encourage more teachers and classrooms to be playing Shut the Box and to discuss the game on this blog, TiPS is offering a promotion. On March 14, we will select four people at random from among the individuals who post in the comments section. These four individuals will each receive a set of Shut the Box game boards.

If you find a version of the gameboard that you would like to have, share it in the comments section. Maybe you will be the winner of a set of those gameboards that you post!

Robert C. Schoen, Ph.D. (rschoen@lsi.fsu.edu), is the founder and director of **Teaching is Problem Solving**.