ISAT Grade 8 Functions. Practice it free.

Defines, compares, and uses functions to model relationships. This Grade 8 reporting domain maps to 4 practice skills and 8 representative questions from the playable bank.

Grade 84 mapped skills

What the test measures

Functions skills

Define, evaluate, and compare functions
Use functions to model relationships between quantities
Interpret the rate of change and initial value of a function from a graph, table, or equation

Standards basis

Idaho Content Standards (Mathematics) — Idaho

How the ISAT reports it

Idaho ISAT is a state assessment administered to grades 3–8 and 11 and reported against Idaho grade-level content standards rather than a separate national testing framework. The public ISAT page points to summative blueprints and math specifications, while the Idaho Content Standards page shows the math program is organized by grade-band/domain progressions aligned to Idaho standards.

Blueprint & weighting

The public Idaho ISAT page references summative blueprints and item specifications, but the accessible official page content did not expose a published domain-by-domain percentage blueprint for math.

Official sources

Idaho Department of Education — Idaho Standards Achievement Test (ISAT)
Idaho Department of Education — Idaho Content Standards

Practice by skill

Topics mapped to this domain

Try it now

8 free questions · 0/0 correct

Practice playeasy

What is the $y$ -intercept of the line $y = \dfrac{1}{4}x - 6$ ?

In $y = mx + b$ , the $y$ -intercept is $b = -6$ .

Practice playmedium

For the function $v(x) = 6x + k$ with constant $k$ , it is known that $v(7) = 30$ . What number does $v(4)$ equal?

Substitute $x = 7$ : $6(7) + k = 30$ , so $42 + k = 30$ and $k = -12$ . The rule is $v(x) = 6x - 12$ , so $v(4) = 6(4) - 12 = 24 - 12 = 12$ .

Practice playeasy

Elena already has $\text{\char36}75$ in her savings account and deposits $\text{\char36}20$ each week. Let $x$ be the number of weeks and $y$ be the account balance in dollars. Which equation models the situation?

She starts at $\text{\char36}75$ (intercept) and gains $\text{\char36}20$ per week (slope), so $y = 20x + 75\textsf{.}$

Practice playeasy

What is the slope of the line through $(-1, 4)$ and $(2, -5)$ ?

Slope $= \dfrac{-5 - 4}{2 - (-1)} = \dfrac{-9}{3} = -3\textsf{.}$

Practice playeasy

What is the slope of the line $y = \dfrac{3}{2}x + 2$ ?

In $y = mx + b$ , the slope is $m = \dfrac{3}{2}$ .

Practice playmedium

Here $c$ is a constant in the rule $w(x) = cx - 15$ . Because $w(4) = 5$ , what must $w(9)$ be?

Substitute $x = 4$ : $4c - 15 = 5$ , so $4c = 20$ and $c = 5$ . The rule is $w(x) = 5x - 15$ , so $w(9) = 5(9) - 15 = 45 - 15 = 30$ .

Practice playeasy

A phone plan costs $\text{\char36}25$ per month plus $\text{\char36}0.08$ for each text message. Let $x$ be the number of texts and $y$ be the monthly bill in dollars. Which equation models the situation?