Hi Danette,

The workbook means a rectangular array. I am going to consider 12 rather than 72. Here is a 3 by 4 array of 12 marbles. (Mathematicians always mention the rows first then the columns.)

A 4 by 3 array would be

or you might have a 2 by 6 array

Arithmetically you are asking to write 12 as the product of two positive integers and then forming an array with these integers. It might even be 1 by 12.

In the array all the rows must have the same number of marbles and all the columns must have the same number of marbles.

Penny