Hi Sheila,
A while ago I answered a similar question about an array of 100 pennies. I suggest that you look there for the mathematical meaning of the term array. By saying "by years" I expect the teacher wants all the pennies in any row to have the same year on them. So if you have 50 pennies from the year 2003 and 50 pennies with the year 1993 you could make a 2 by 50 array with the 1993 pennies in the first row and the 2003 pennies in the second row.
Penny
