The Common Core in Kentucky

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Skills available for Kentucky eighth-grade math standards

Standards are in black and IXL math skills are in dark green. Hold your mouse over the name of a skill to view a sample question. Click on the name of a skill to practice that skill.

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Kentucky Academic Standards Kentucky Academic Standards
Common Core State Standards: Grade 8 Common Core State Standards: Grade 8
Common Core State Standards: Mathematical Practices Common Core State Standards: Mathematical Practices

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KY.8.NS The Number System

Know that there are numbers that are not rational and approximate them by rational numbers.
- KY.8.NS.1 Understand informally that every number has a decimal expansion; the rational numbers are those with decimal expansions that terminate in 0s or eventually repeat. Know that other numbers are called irrational.
- KY.8.NS.2 Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram and estimate the value of expressions.
- Checkpoint opportunity
  - Checkpoint: Rational and irrational numbers (8-I.5)
  - Checkpoint: Approximate irrational numbers (8-I.6)

KY.8.EE Expressions and Equations

Work with radicals and integer exponents.
- KY.8.EE.1 Know and apply the properties of integer exponents to generate equivalent numerical expressions.
- KY.8.EE.2 Use square root and cube root symbols to represent solutions to equations of the form x² = p and x³ = p, where p is a positive rational number. Evaluate square roots of small perfect squares and cube roots of small perfect cubes. Know that perfect squares and perfect cubes are rational.
- KY.8.EE.3 Use numbers expressed in the form of a single digit times an integer power of 10 (Scientific Notation) to estimate very large or very small quantities and express how many times larger or smaller one is than the other.
  - Convert between standard and scientific notation (8-E.1)
  - Compare numbers written in scientific notation (8-E.3)
- KY.8.EE.4 Perform operations with numbers expressed in scientific notation, including problems where both decimal and scientific notation are used. Use scientific notation and choose units of appropriate size for measurements of very large or very small quantities. Interpret scientific notation that has been generated by technology.
- Checkpoint opportunity
Understand the connections between proportional relationships, lines and linear equations.
- KY.8.EE.5 Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in different ways.
  - Find the constant of proportionality from a graph (8-K.4)
  - Graph proportional relationships and find the slope (8-K.9)
- KY.8.EE.6 Use similar triangles to explain why the slope, m, is the same between any two distinct points on a non-vertical line in the coordinate plane; know the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.
- Checkpoint opportunity
  - Checkpoint: Proportional relationships (8-K.16)
  - Checkpoint: Slope and linear equations (8-AA.17)
Analyze and solve linear equations and pairs of simultaneous linear equations.
- KY.8.EE.7 Solve linear equations in one variable.
  - KY.8.EE.7.a Give examples of linear equations in one variable with one solution, infinitely many solutions, or no solutions. Show which of these possibilities is the case by successively transforming the given equation into simpler forms, until an equivalent equation of the form x = a, a = a, or a = b results (where a and b are different numbers).
    - Find the number of solutions (8-Y.19)
    - Create equations with no solutions or infinitely many solutions (8-Y.20)
  - KY.8.EE.7.b Solve linear equations with rational number coefficients, including equations whose solutions require expanding expressions using the distributive property and combining like terms.
- KY.8.EE.8 Analyze and solve a system of two linear equations.
  - KY.8.EE.8.a Understand that solutions to a system of two linear equations in two variables correspond to points of intersection of their graphs, because points of intersection satisfy both equations simultaneously; understand that a system of two linear equations may have one solution, no solution, or infinitely many solutions.
  - KY.8.EE.8.b Solve systems of two linear equations in two variables algebraically by using substitution where at least one equation contains at least one variable whose coefficient is 1 and by inspection for simple cases.
    - Find the number of solutions to a system of equations (8-CC.5)
    - Solve a system of equations using substitution (8-CC.8)
  - KY.8.EE.8.c Solve real-world and mathematical problems leading to two linear equations in two variables.
    - Solve a system of equations by graphing: word problems (8-CC.3)
    - Solve a system of equations using substitution: word problems (8-CC.9)
- Checkpoint opportunity
  - Checkpoint: Solve linear equations (8-Y.21)
  - Checkpoint: Systems of equations (8)

KY.8.F Functions

Define, evaluate and compare functions.
- KY.8.F.1 Understand that a function is a rule that assigns to each input exactly one output. The graph of a function is the set of ordered pairs consisting of an input and the corresponding output.
- KY.8.F.2 Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions).
  - Compare linear functions: graphs and equations (8-BB.15)
  - Compare linear functions: tables, graphs, and equations (8-BB.16)
- KY.8.F.3 Understand properties of linear functions.
  - KY.8.F.3.a Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line.
    - Graph a line from an equation in slope-intercept form (8-AA.6)
  - KY.8.F.3.b Identify and give examples of functions that are not linear.
    - Identify linear and nonlinear functions: graphs and equations (8-BB.19)
    - Identify linear and nonlinear functions: tables (8-BB.20)
- Checkpoint opportunity
Use functions to model relationships between quantities.
- KY.8.F.4 Construct a function to model a linear relationship between two quantities.
  - KY.8.F.4.a Determine the rate of change and initial value of the function from a description of a relationship or from two (x, y) values, including reading these from a table or from a graph.
  - KY.8.F.4.b Interpret the rate of change and initial value of a linear function in terms of the situation it models and in terms of its graph or a table of values.
    - Interpret the slope and y-intercept of a linear function (8-BB.13)
- KY.8.F.5 Use graphs to represent functions.
  - KY.8.F.5.a Describe qualitatively the functional relationship between two quantities by analyzing a graph.
    - Write linear functions: word problems (8-BB.17)
  - KY.8.F.5.b Sketch a graph that exhibits the qualitative features of a function that has been described verbally.
    - Identify graphs: word problems (8-BB.)
- Checkpoint opportunity
  - Checkpoint: Construct and interpret linear functions (8-BB.29)
  - Checkpoint: Sketch and describe graphs (8-BB.30)

KY.8.G Geometry

Understand congruence and similarity using physical models, transparencies, or geometry software.
- KY.8.G.1 Verify experimentally the properties of rotations, reflections and translations:
  - KY.8.G.1.1 Lines are congruent to lines.
  - KY.8.G.1.2 Line segments are congruent to line segments of the same length.
  - KY.8.G.1.3 Angles are congruent to angles of the same measure.
  - KY.8.G.1.4 Parallel lines are congruent to parallel lines.
- KY.8.G.2 Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections and translations. Given two congruent figures, describe a sequence that exhibits the congruence between them.
- KY.8.G.3 Describe the effect of dilations, translations, rotations and reflections on two-dimensional figures using coordinates.
- KY.8.G.4 Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations and dilations. Given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
  - Similar and congruent figures (8-S.1)
  - Side lengths and angle measures of similar figures (8-S.8)
- KY.8.G.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal and the angle-angle criterion for similarity of triangles.
- Checkpoint opportunity
Understand and apply the Pythagorean Theorem.
- KY.8.G.6 Explain a proof of the Pythagorean Theorem and its converse.
  - Converse of the Pythagorean theorem: is it a right triangle? (8-T.6)
- KY.8.G.7 Apply the Pythagorean Theorem to determine unknown side lengths in right triangles in real-world and mathematical problems in two and three dimensions.
- KY.8.G.8 Apply the Pythagorean Theorem to find the distance between two points in a coordinate system.
  - Find the distance between two points (8-P.4)
- Checkpoint opportunity
  - Checkpoint: Pythagorean theorem and its converse (8-T.7)
  - Checkpoint: Applications of the Pythagorean theorem (8-T.8)
Solve real-world and mathematical problems involving volume of cylinders, cones and spheres.
- KY.8.G.9 Apply the formulas for the volumes and surface areas of cones, cylinders and spheres and use them to solve real-world and mathematical problems.
- Checkpoint opportunity
  - Checkpoint: Volume (8-V.18)

KY.8.SP Statistics and Probability

Investigate patterns of association in bivariate data.
- KY.8.SP.1 Construct and interpret scatter plots for bivariate numerical data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association and nonlinear association.
- KY.8.SP.2 Know that lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a line and informally assess the model fit by judging the closeness of the data points to the line.
  - Identify lines of best fit (8-FF.10)
  - Write equations for lines of best fit (8-FF.11)
- KY.8.SP.3 Use the equation of a linear model to solve problems in the context of bivariate numerical data, interpreting the slope and intercept.
- Checkpoint opportunity

The Common Core in Kentucky

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KY.8.NS The Number System

Know that there are numbers that are not rational and approximate them by rational numbers.

KY.8.NS.1 Understand informally that every number has a decimal expansion; the rational numbers are those with decimal expansions that terminate in 0s or eventually repeat. Know that other numbers are called irrational.

KY.8.NS.2 Use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram and estimate the value of expressions.

Checkpoint opportunity

KY.8.EE Expressions and Equations

Work with radicals and integer exponents.

KY.8.EE.1 Know and apply the properties of integer exponents to generate equivalent numerical expressions.

KY.8.EE.2 Use square root and cube root symbols to represent solutions to equations of the form x² = p and x³ = p, where p is a positive rational number. Evaluate square roots of small perfect squares and cube roots of small perfect cubes. Know that perfect squares and perfect cubes are rational.

KY.8.EE.3 Use numbers expressed in the form of a single digit times an integer power of 10 (Scientific Notation) to estimate very large or very small quantities and express how many times larger or smaller one is than the other.

Checkpoint opportunity

Understand the connections between proportional relationships, lines and linear equations.

KY.8.EE.5 Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in different ways.

KY.8.EE.6 Use similar triangles to explain why the slope, m, is the same between any two distinct points on a non-vertical line in the coordinate plane; know the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.

Checkpoint opportunity

Analyze and solve linear equations and pairs of simultaneous linear equations.

KY.8.EE.7 Solve linear equations in one variable.

KY.8.EE.7.b Solve linear equations with rational number coefficients, including equations whose solutions require expanding expressions using the distributive property and combining like terms.

KY.8.EE.8 Analyze and solve a system of two linear equations.

KY.8.EE.8.b Solve systems of two linear equations in two variables algebraically by using substitution where at least one equation contains at least one variable whose coefficient is 1 and by inspection for simple cases.

KY.8.EE.8.c Solve real-world and mathematical problems leading to two linear equations in two variables.

Checkpoint opportunity

KY.8.F Functions

Define, evaluate and compare functions.

KY.8.F.1 Understand that a function is a rule that assigns to each input exactly one output. The graph of a function is the set of ordered pairs consisting of an input and the corresponding output.

KY.8.F.2 Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions).

KY.8.F.3 Understand properties of linear functions.

KY.8.F.3.a Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line.

KY.8.F.3.b Identify and give examples of functions that are not linear.

Checkpoint opportunity

Use functions to model relationships between quantities.

KY.8.F.4 Construct a function to model a linear relationship between two quantities.

KY.8.F.4.a Determine the rate of change and initial value of the function from a description of a relationship or from two (x, y) values, including reading these from a table or from a graph.

KY.8.F.4.b Interpret the rate of change and initial value of a linear function in terms of the situation it models and in terms of its graph or a table of values.

KY.8.F.5 Use graphs to represent functions.

KY.8.F.5.a Describe qualitatively the functional relationship between two quantities by analyzing a graph.

KY.8.F.5.b Sketch a graph that exhibits the qualitative features of a function that has been described verbally.

Checkpoint opportunity

KY.8.G Geometry

Understand congruence and similarity using physical models, transparencies, or geometry software.

KY.8.G.1 Verify experimentally the properties of rotations, reflections and translations:

KY.8.G.1.1 Lines are congruent to lines.

KY.8.G.1.2 Line segments are congruent to line segments of the same length.

KY.8.G.1.3 Angles are congruent to angles of the same measure.

KY.8.G.1.4 Parallel lines are congruent to parallel lines.

KY.8.G.2 Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections and translations. Given two congruent figures, describe a sequence that exhibits the congruence between them.

KY.8.G.3 Describe the effect of dilations, translations, rotations and reflections on two-dimensional figures using coordinates.

KY.8.G.4 Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations and dilations. Given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.

KY.8.G.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal and the angle-angle criterion for similarity of triangles.

Checkpoint opportunity

Understand and apply the Pythagorean Theorem.

KY.8.G.6 Explain a proof of the Pythagorean Theorem and its converse.

KY.8.G.7 Apply the Pythagorean Theorem to determine unknown side lengths in right triangles in real-world and mathematical problems in two and three dimensions.

KY.8.G.8 Apply the Pythagorean Theorem to find the distance between two points in a coordinate system.

Checkpoint opportunity

Solve real-world and mathematical problems involving volume of cylinders, cones and spheres.

KY.8.G.9 Apply the formulas for the volumes and surface areas of cones, cylinders and spheres and use them to solve real-world and mathematical problems.

Checkpoint opportunity

KY.8.SP Statistics and Probability

Investigate patterns of association in bivariate data.

KY.8.SP.1 Construct and interpret scatter plots for bivariate numerical data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association and nonlinear association.

KY.8.SP.2 Know that lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a line and informally assess the model fit by judging the closeness of the data points to the line.

KY.8.SP.3 Use the equation of a linear model to solve problems in the context of bivariate numerical data, interpreting the slope and intercept.

Checkpoint opportunity