Page 170 - IM_Algebra2_FL Print Sample.pdf

Lesson 10: Adding Up
• Find the sums of simple nite geometric sequences, without use of formulas. Lesson Narrative
In this lesson students encounter a few situations where they need to nd the sum of a sequence. At this point, they just add terms in preparation for a future unit, where they will encounter a need to develop a formula to add the terms of a geometric sequence.
Required Materials Blank paper
Scissors
Required Preparation
The rst activity describes a speci c process for cutting and distributing paper. If you choose for students to act out this process to better understand the context, prepare 1 piece of blank paper and 1 pair of scissors for every 4 students. (The paper can’t be reused, since it will be cut into pieces.)
Student Learning Goals
• Let’s look at sequences and the sum of their terms. 10.1 Math Talk: Adding Terms
Warm Up: 10 minutes
The purpose of this Math Talk is to elicit strategies and understandings students have for adding fractions. These understandings help students develop uency and will be helpful later in this lesson when students will need to be able to add and subtract fractions. Math Talks build uency by encouraging students to think about expressions or diagrams and rely on what they know about properties of operations to mentally solve a problem.
Instructional Routines
• Math talk
What: In these warm-ups, one problem is displayed at a time. Students are given a few minutes to quietly think and give a signal when they have an answer and a strategy. The teacher selects students to share di erent strategies for each problem, “Who thought about it a di erent way?” Their explanations are recorded for all to see. Students might be pressed to provide more details about why they decided to approach a problem a certain way. It may not be possible to share every possible strategy for the given limited time; the teacher may only gather two or three distinctive strategies per problem. Problems are purposefully chosen to elicit di erent approaches, often in a way that builds from one problem to the next.
Unit 1
Lesson 10: Adding Up 105