Average is sum of observations (numbers) divided by number of observations. Average is also called Arithmetic Mean or simply Mean. Average for numbers in arithmetic sequence is the average of the smallest and the largest numbers in the sequence.
Maze - Find the Arithmetic Mean (middle term) of an Arithmetic Sequence from nevergiveuponmath on TeachersNotebook.com - (4 pages) - This activity is a review of understanding how to find the "Arithmetic Mean". This maze requires students to "Find the Arithmetic Mean of an arithmetic sequence given the term before and after.
ARITHMETIC MEAN ARITHMETIC SERIES ARITHMETIC MEAN ARITHMETIC MEAN Finding a certain number of terms between two given terms of an arithmetic sequenc. http://slidehot.com/resources/arithmetic-mean-arithmetic-series.42999/