I developed the topic of finding the sum of an infinite series with Matthew by referring to a graph of the sum of the series of one-half, one-quarter, one-eighth,... to show him that the sum approaches 1 as the number of terms approaches infinity. I then showed him the formula and explained how to use it and the conditions for it to have an answer. We also explored non-terminating decimals. I gave him a homework assignment of exercises p.823 # 9 - 33 multiples of 3.