Mississippi Math F-IF.3

MathGrades 9–12Interpreting Functions

The Standard

Use the fact that sequences are functions whose domain is a subset of the integers to identify sequences and generate their explicit formulas.

2025 Mississippi College- and Career-Readiness Standards for Mathematics · Understand the Concept of a Function and use Function Notation

Teacher's field guide

What Students Need to Do: Students identify sequences as functions with whole-number positions as inputs. They write a rule that finds any term directly, without finding earlier terms first. They check whether numbering starts at 0 or 1.
What Mastery Looks Like: For 5, 8, 11, 14, a student writes aₙ = 3n + 2 when n starts at 1. They use the rule to find the 20th term, 62. They know that 2.5 is not a position in this sequence.
Common Misconceptions: Students may use the wrong rule because they overlook whether the first position is 0 or 1. Some write a rule that depends on the previous term when asked for a direct formula. Others assume the terms themselves must be whole numbers.
How to Assess It: Exit ticket: The first four terms are 2, 6, 18, 54, with n starting at 1. Write a rule for the nth term and use it to find the fifth term.

Lesson moves

Have students build squares with 1, 4, 9, and 16 tiles, record the tile count at each position, and write aₙ = n².
Show 5, 8, 11, 14 with n starting at 0; ask students to explain why 3n + 5 works but 3n + 2 does not.
Give cards showing 4, 7, 10, 13 and 2, 6, 18, 54; students match them to 3n + 1 and 2 × 3⁽ⁿ⁻¹⁾.
Describe a weekly deposit of $5 that rises by $3 each week; students write a rule for the deposit in week n.

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