Mississippi Math ATM.F.31

MathGrades 9–12Functions

The Standard

Write a function that describes a relationship between two quantities; and be able to calculate and interpret the average rate of change of a function (presented symbolically or as a table) over a specified interval. Estimate the rate of change from a graph.

2025 Mississippi College- and Career-Readiness Standards for Mathematics · Expressions, Equations and Functions

Teacher's field guide

What This Standard Means

What Students Need to Do: Students write a rule that gives one quantity from another. They find how much the output changes for each unit of input using a rule or table. They estimate that rate from two points on a graph.
What Mastery Looks Like: For a tank holding 40 liters at minute 1 and 25 liters at minute 4, a student writes V(t) = 45 - 5t, assuming steady draining. They calculate a rate of -5 liters per minute and explain that the tank is losing water. They can estimate that rate from a graph.
Common Misconceptions: Students may divide the output values instead of finding their difference. Others reverse only one subtraction and get the wrong sign. On graphs, they may use a point's height instead of the change between two points.
How to Assess It: Exit ticket: Give a table and matching straight-line graph of tank volume, with (1 minute, 40 liters) and (4 minutes, 25 liters). Ask for a volume rule, the rate from the table, an estimate from the graph, and what the sign and units mean.

Lesson moves

Ways to Teach It

Pour one cup into a straight-sided clear container each minute, record water height, and write a height rule from the measurements.
Show tank volume falling from 40 liters to 25 liters in three minutes; ask students to explain the rate in one sentence.
Give pairs formula, table, and graph cards with marked intervals; have them calculate or estimate each rate and match equal rates.
Give battery readings of 80% at noon and 50% at 3 p.m.; assume steady drain, then write a rule and explain its slope.

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