The point of this Quick Write is to get students thinking about their prior knowledge coming into this section. Place the following question on the board:
"Using your vocabulary list from the vocabulary lesson, what is the difference between sequences and series?"
I am looking for their vocabulary understanding and a few sentences using these words such as, "a series is the summation of a sequence". I discuss this as a class after they complete the Quick Write and also grade it during their binder checks after each unit.
In this section I use the previous knowledge that the students have to discuss the differences between series and sequences. I purposefully use the Louvre square pyramid problem from the arithmetic sequences lesson and develop it further into a series problem. The students model series in various ways (MP#4) and derive the formula for summation of an arithmetic series. Although this is not listed in the CCSS, the derivation of geometric series formula (A-SSE.B.4) is. Deriving the formula for arithmetic series allows students the opportunity to see how to derive a formula and lends coherence when deriving the geometric series formula.
During this section, students are given the attached handout and are asked to "Find Someone Who" can fill out a missing part of the 6 model representation sheet. They can only use each person once and that person has to initial that section. Once complete with each section, it is the students responsibility to check over the work of their peers. If they do not agree, they need to correct an discuss with that person. If they do agree they need to initial next to the section. Once complete, students check their papers against a key and are responsible for fixing sections that are incorrect.