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Ideas for the K-6 Classroom: The Game of Krypto to Support Number Sense Dana T. Johnson

The purpose of this article is to share a teaching activity that is useful and powerful for instruction, motivation of students, and enrichment in math classrooms for grades 3 – 8. It is also a great game to teach to families. The game of

can be found through internet search terms “NCTM and Krypto.” Mental arithmetic is the preferred method of solving the hands. Some students may be al- lowed to work with paper and pencil. For young

students or those who need a more concrete approach, you may have them write the six numbers on a long strip of scrap paper. Then they tear the numbers apart, thus creating their own set of mini-cards for the hand. Some students are more suc- cessful when they can physically rearrange the numbers. When you work with young students, you may want to use only the numbers 1-10. For primary grade stu-

Krypto is a card game that consists of 56 cards. In the deck there are three each of the numbers 1 – 6, four each of 7 – 10, two each of 11 – 17, and one each of 18 – 25. Play begins by dealing a set of six numbers. The first five are combined in any order along with any of the operations +, –, x, or ÷ to obtain a result equal to the sixth number (called the objective or target num- ber).

For example, suppose the numbers dealt are 20, 15, 17, 3, 9, and 4. Here is a solution: 20 ÷ [(17 -15) + (9 ÷ 3)] = 4. This game is similar to the game called “24,” which uses four numbers that are printed on a card to get the objective number 24. In Krypto, the purpose of the cards is to generate numbers for use in the game. If you do not have cards in your classroom and you are playing as a whole-class activity, you may simply ask six students to choose a number between 1 and 25. Write the numbers on the board and have everyone work to find a solution. When a student finds a solution, s/he calls “Krypto” and explains it to the class. Students may also play in small groups with a deck of cards. The game is also an excellent soli- taire game. The National Council of Teachers of Mathematics has an online version of the game that

dents, you may allow them to solve the hand using fewer than all five numbers. For example, suppose the numbers dealt are 4, 3, 6, 8, 1 with an objective number of 7. Students may find solutions such as: 2-number solutions: 4 + 3 = 7 6 + 1 = 7 8 - 1 = 7 3-number solution: 4 + 6 – 3 = 7 4-number solution: 6 ÷ 3 x 4 – 1 = 7 5- number solution: 6 ÷ (8 ÷ 4) + 3 + 1 = 7 This strategy allows students to differentiate the activity for their own level of comfort. Over the last few decades I have played this game with students in grades 3 to 12. No one has ever cared much about scoring. The satisfaction seems to be in finding a solution or seeing someone else find one. Sometimes several students share

Virginia Mathematics Teacher vol. 44, no. 1

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