## Reflection: Connection to Prior Knowledge The Recursive Process with Arithmetic Sequences - Section 4: Exit Slip

On today's Exit Slip, several students did find the total number of cans needed for the display by totaling the numbers in each row.  I show this in this student example.  This student makes a mistake after adding 14 cans to the next row, skipping 15, and adding 16 to the next row.  This mistake gives the student a sum of 216 instead of the correct answer of 231 cans. The second example shows the correct sum of 231 cans if the student had not skipped adding 15.

In class I used both of these examples to show the correct answer of 231 cans when providing feedback to the students.  I then introduced finding the sum of a finite arithmetic series.  I showed students how to:

1. Take the average of the first and last term by adding 1 + 21 and dividing by 2.
2. Multiply this average by the number of terms (which is 21 in this case)

The product confirms that the sum of the arithmetic series is 231 cans for the display.

Connection to Prior Knowledge: Looking at Student Work

# The Recursive Process with Arithmetic Sequences

Unit 3: Linear Functions
Lesson 2 of 20

## Big Idea: This lesson takes students from the simple concrete problem of seating 4 people around a square table to the more abstract problem of finding the nth term.

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Standards:
Subject(s):
Math, independent practice, guided practice, Recursive Formula for a linear function, 4 people around a table problem, find the nth term of an arithmetic sequence, common difference
50 minutes

### Rhonda Leichliter

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