Remind them to continue play until they find a pattern. As the students play the game, circulate among them. Note the students that are using particular recording methods to solve the problem, but allow them to find their own method of recording. If there is time, have the students try the patterns found using 9 cards instead of 10 cards. If the game is played with 9 cards, instead of a fixed end point, a cycle occurs.
Nice numbers turn out to be triangular numbers.
Illustrate a square and a triangular number on the board. A number that can be shown as a square array of dots is called a square number. Similarly, a number that can be shown as a triangular array is called a triangular number. Note that the shape of the triangle is not important. There are two ways of arranging 10 dots.