We found this great article by Will Shortz in the Feb 8th online issue of the New York Times.
The puzzle requires tons of math skills practice and provides a fun and enjoyable way for children to gain the necessary repetition in the exercises to remember basic skills.
"The rules are simple: Fill the grid with digits so as not to repeat a digit within any row or column, and so the digits within each heavily outlined box (called a cage) go together using the arithmetic operation shown to make the target number indicated.
Two new KenKen puzzles will be presented in The Times each day from Monday through Saturday. The first is a four-by-four-square puzzle that increases in difficulty from easy to medium as the week progresses. The second is a six-by-six-square puzzle that goes from medium to hard.
KenKen was invented in 2004 by the Japanese educator Tetsuya Miyamoto, who founded and teaches at the Miyamoto Math Classroom in Tokyo. Students attend his class on weekends to improve their math and thinking skills. Mr. Miyamoto said he believes in “the art of teaching without teaching.”
He provides the tools for students to learn at their own pace using their own trial-and-error methods. If these tools are engaging enough, he said, students are more motivated and learn better than they would through formal instruction.
About 90 minutes of class time each week is set aside for solving puzzles, usually designed by Mr. Miyamoto. The most popular one has been KenKen."
Read the original NYTimes online article here.