Maryland Math 6.AT.C.8.a
The Standard
- 6.AT.C.8
- Solve problems in context by writing and solving equations and interpreting the solutions in context.
Explain that a variable can represent an unknown number and use substitution to determine whether a given number makes an equation true.
Maryland College and Career Ready Standards for Mathematics (2025) · REASON ABOUT AND SOLVE ONE-VARIABLE EQUATIONS AND INEQUALITIES
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students use a letter to stand for an unknown number in an equation. They replace the letter with a given number, calculate both sides, and decide whether the equation is true.
What Mastery Looks Like
- A student substitutes a given number and compares both sides of the equation. They show that x=5 works in 3x+2=17 and reject x=6 because 3(6)+2=20, not 17.
Common Misconceptions
- Some students read 3x as 3+x rather than 3 times x. Others calculate only one side of the equation or think a number works because the two sides are close.
How to Assess It
- Exit ticket: For 3x+2=17, test x=5 and x=6 by substituting each value and comparing both sides.
Lesson moves
Ways to Teach It
Put counters under a cup and three beside it; state there are seven total, then test x=4 in x+3=7.
Have partners write why x=5 works in 2x+1=11 but x=4 does not, using both substituted calculations.
Make cards with x+4=9 and x=5 or x=6; pairs sort matches and mismatches, then show each substitution.
Write 'Two tickets plus a $3 fee cost $19' on the board; students test whether $8 per ticket fits 2t+3=19.
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Printable 6.AT.C.8.a Worksheet
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Related Standards
- 7.AT.C.9
Use variables to represent quantities and write and solve inequalities to model and reason about constraints and conditions in context.
- 7.AT.C.8
Use variables to represent quantities and write and solve equations to model and reason about relationships in context.
- 6.AT.C.10.a
Explain that a variable can represent an unknown number in a set and use substitution to determine whether a given number in a set makes an inequality true.
- 3.AT.A.2.a
Represent these problems using equations with a letter standing for the unknown quantity.
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