8.8.A
The Standard
write one-variable equations or inequalities with variables on both sides that represent problems using rational number coefficients and constants
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students turn a situation into two expressions that share the same unknown quantity. They connect the expressions with an equal sign or comparison symbol and include fractions, decimals, or negative values when needed.
What Mastery Looks Like
- Students define the variable and build a correct expression for each side of a comparison. They choose an equality or inequality symbol that matches the situation and use decimals, fractions, and negative values accurately.
Common Misconceptions
- Students may put every term on one side instead of representing each quantity separately. They often reverse inequality symbols, omit fixed costs, or attach a coefficient to the wrong quantity.
How to Assess It
- Exit ticket: Plan A costs $12 plus $2.50 per visit. Plan B costs $30 plus $1 per visit. Write an equation for equal costs and an inequality for when Plan A costs more.
Lesson moves
Ways to Teach It
Use balance scales, cups, and labeled weights to model two changing costs, then have students write the matching equation.
Ask, “How does the word ‘than’ affect the comparison?” Students explain their reasoning with one equation and one inequality.
Play a context-match relay with cards showing stories, equations, inequalities, and graphs; teams justify each four-card set.
Compare two phone plans with monthly fees and per-gigabyte charges, then write when one plan costs less.
Keep exploring
Related Standards
- 8.8.C
model and solve one-variable equations with variables on both sides of the equal sign that represent mathematical and real-world problems using rational number ...
- 6.9.A
write one-variable, one-step equations and inequalities to represent constraints or conditions within problems
- 7.10.A
write one-variable, two-step equations and inequalities to represent constraints or conditions within problems
- 8.8.B
write a corresponding real-world problem when given a one-variable equation or inequality with variables on both sides of the equal sign using rational number c...
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