CCSS.Math.Content.HSA-REI.A
Standard Cluster
Understand solving equations as a process of reasoning and explain the reasoning
Common Core State Standards for Mathematics · High School — Algebra
Cluster contents
Standards in This Cluster
CCSS.Math.Content.HSA-REI.A is a cluster heading. These are the individual standards under it.
- CCSS.Math.Content.HSA-REI.A.1
Explain each step in solving a simple equation as following from the equality of numbers asserted at the previous step, starting from the assumption that the or...
- CCSS.Math.Content.HSA-REI.A.2
Solve simple rational and radical equations in one variable, and give examples showing how extraneous solutions may arise.
Teacher's field guide
What This Cluster Means
What Students Need to Do
- Students treat solving as a chain of justified moves, not a list of memorized steps. They explain why each transformation keeps the same solutions and check for results that do not satisfy the original equation.
What Mastery Looks Like
- Students solve equations while naming the property or logical reason that supports each step. They check possible solutions in the original equation and identify results introduced by squaring, taking powers, or clearing denominators.
Common Misconceptions
- Students may apply an operation to only one side or cancel terms that are joined by addition. They may also accept every result from squaring or clearing denominators without checking it in the original equation.
How to Assess It
- Give the equation √(x + 5) = x - 1 and ask students to solve it, check each result, and explain why any result is rejected.
Lesson moves
Ways to Teach It
Give pairs equation-step cards to arrange into a valid solution, then have students label the reason for each move.
Ask students to explain in writing why adding the same number to both sides preserves the solution set.
Play Error Detective with worked solutions that include illegal cancellation, one-sided operations, or unchecked extraneous results.
Use a ladder-length equation with a square root, then compare the algebraic answers with lengths that make sense in the diagram.
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Printable HSA-REI.A Worksheet
A ready-to-print activity worksheet aligned to CCSS.Math.Content.HSA-REI.A, with an answer key for the teacher on its own page. No account needed.
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Related Standards
- CCSS.Math.Content.6.EE.B
Reason about and solve one-variable equations and inequalities.
- CCSS.Math.Content.6.EE.B.5
Understand solving an equation or inequality as a process of answering a question: which values from a specified set, if any, make the equation or inequality tr...
- CCSS.Math.Content.6.RP.A
Understand ratio concepts and use ratio reasoning to solve problems.
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