Chapter 4 · Lesson 7 of 10 · Grade 6 · Expressions & Equations · MAT-06-EE-007
Solve One-Step Addition and Subtraction Equations
Represent and solve solve one-step addition and subtraction equations problems using precise mathematical notation, models, and reasoning.
Math V4 · Course chapter
Chapter 4: Expressions, Equations, and Inequalities
Using symbols to describe relationships
Essential question: How can a verbal or numerical relationship be expressed symbolically, transformed without changing its meaning, and solved?
Where this lesson fits
Lesson 7 of 10. Each lesson builds on earlier chapter representations and ideas rather than resetting the topic.
Chapter destination
Model a real pricing or distance situation with variables, expressions, equations, inequalities, tables, and graphs.
Learning objectives
What you should be able to do
- Represent and solve solve one-step addition and subtraction equations problems using precise mathematical notation, models, and reasoning.
- Explain why a method for solve one-step addition and subtraction equations works, interpret the result in context, and verify it independently.
Prerequisite check
Make sure the foundation is ready.
The new lesson depends on this prerequisite as active knowledge.
Learn
Build the idea from meaning, not memorization.
Chapter 4: Expressions, Equations, and Inequalities
Using symbols to describe relationships. This is Lesson 7 of 10 in Chapter 4. It builds on earlier chapter ideas instead of restarting the topic from scratch.
Connection to the course
Cumulative knowledge used here includes Chapter 1 rates, Chapter 2 operation fluency, Chapter 3 signed quantities. As you work, connect today's idea to earlier lessons in the chapter and keep those earlier representations available for comparison.
Mathematical meaning
Solve One-Step Addition and Subtraction Equations uses symbols to describe relationships. Equality and inequality are relationships that must be preserved on both sides.
Represent the relationship
The Math Box uses equation balance to expose the structure. Change one input, predict the result, then connect the visual change to an equation, table, graph, number line, or geometric model.
Calculate, interpret, and verify
Verify algebra by substituting the proposed solution into the original statement; equivalent expressions must agree for the same input.
Math Box · Interactive lesson
Touch the math. Change it. See what stays true.
Use the interactive model before and after the worked examples. Change the inputs, make a prediction, then use the model to test whether your reasoning holds.
Equation Balance
Adjust both sides. Equality means both expressions have the same value.
Balanced: both sides have equal value.
- Model one example of solve one step addition and subtraction equations in the Math Box.
- Change one input, predict the effect, and test the prediction.
- Connect the model to another representation used earlier in this chapter.
- State the relationship or invariant that explains what stayed mathematically consistent.
Worked examples
Twenty different ways to see the concept work.
Solve x + 3 = 5.
x = 5 − 3 = 2Subtract the same value from both sides.
Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 8.
x = 8 − 5 = 3The representation should show the same mathematical relationship as the calculation. Subtract the same value from both sides.
Explain why a valid method works, then solve: Solve x + 7 = 11.
x = 11 − 7 = 4A complete explanation names the relationship or property being preserved. Subtract the same value from both sides.
Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 14.
x = 14 − 9 = 5The estimate is a reasonableness check, not a replacement for the exact result. Subtract the same value from both sides.
Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 9.
x = 9 − 3 = 6Verification should independently support the result. Subtract the same value from both sides.
Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 12.
x = 12 − 5 = 7State the result with its meaning, units, direction, or comparison—not only a number. Subtract the same value from both sides.
Error analysis: a student says, "Changing only one side of an equation." Explain the mistake, then solve this related task correctly: Solve x + 7 = 15.
Use equivalent operations on both sides. Correct solution: x = 15 − 7 = 8Error analysis requires identifying the broken idea, not merely replacing the final answer. Subtract the same value from both sides.
Compare two related cases and explain what changes and what stays mathematically consistent. Case A: Solve x + 9 = 18. Case B: Solve x + 3 = 12.
Case A: x = 18 − 9 = 9 Case B: x = 12 − 3 = 9Compare the structure, representation, units, and result rather than only the numbers. Subtract the same value from both sides.
Solve x + 3 = 13.
x = 13 − 3 = 10Subtract the same value from both sides.
Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 7.
x = 7 − 5 = 2The representation should show the same mathematical relationship as the calculation. Subtract the same value from both sides.
Explain why a valid method works, then solve: Solve x + 7 = 10.
x = 10 − 7 = 3A complete explanation names the relationship or property being preserved. Subtract the same value from both sides.
Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 13.
x = 13 − 9 = 4The estimate is a reasonableness check, not a replacement for the exact result. Subtract the same value from both sides.
Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 8.
x = 8 − 3 = 5Verification should independently support the result. Subtract the same value from both sides.
Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 11.
x = 11 − 5 = 6State the result with its meaning, units, direction, or comparison—not only a number. Subtract the same value from both sides.
Error analysis: a student says, "Changing only one side of an equation." Explain the mistake, then solve this related task correctly: Solve x + 7 = 14.
Use equivalent operations on both sides. Correct solution: x = 14 − 7 = 7Error analysis requires identifying the broken idea, not merely replacing the final answer. Subtract the same value from both sides.
Compare two related cases and explain what changes and what stays mathematically consistent. Case A: Solve x + 9 = 17. Case B: Solve x + 3 = 11.
Case A: x = 17 − 9 = 8 Case B: x = 11 − 3 = 8Compare the structure, representation, units, and result rather than only the numbers. Subtract the same value from both sides.
Solve x + 3 = 12.
x = 12 − 3 = 9Subtract the same value from both sides.
Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 15.
x = 15 − 5 = 10The representation should show the same mathematical relationship as the calculation. Subtract the same value from both sides.
Explain why a valid method works, then solve: Solve x + 7 = 9.
x = 9 − 7 = 2A complete explanation names the relationship or property being preserved. Subtract the same value from both sides.
Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 12.
x = 12 − 9 = 3The estimate is a reasonableness check, not a replacement for the exact result. Subtract the same value from both sides.
Practice
Guided practice with hints
01Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 7.
Hint: Choose a representation before computing.
Answer: x = 7 − 3 = 4
02Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 10.
Hint: Explain what relationship or property makes your method valid.
Answer: x = 10 − 5 = 5
03Error analysis: a student says, "Changing only one side of an equation." Explain the mistake, then solve this related task correctly: Solve x + 7 = 13.
Hint: Choose a representation before computing.
Answer: Use equivalent operations on both sides. Correct solution: x = 13 − 7 = 6
04Compare two related cases and explain what changes and what stays mathematically consistent. Case A: Solve x + 9 = 16. Case B: Solve x + 3 = 10.
Hint: Explain what relationship or property makes your method valid.
Answer: Case A: x = 16 − 9 = 7 Case B: x = 10 − 3 = 7
05Solve x + 3 = 11.
Hint: Choose a representation before computing.
Answer: x = 11 − 3 = 8
06Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 14.
Hint: Explain what relationship or property makes your method valid.
Answer: x = 14 − 5 = 9
Practice
Independent practice
01Explain why a valid method works, then solve: Solve x + 7 = 17.
Answer: x = 17 − 7 = 10
02Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 11.
Answer: x = 11 − 9 = 2
03Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 6.
Answer: x = 6 − 3 = 3
04Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 9.
Answer: x = 9 − 5 = 4
05Error analysis: a student says, "Changing only one side of an equation." Explain the mistake, then solve this related task correctly: Solve x + 7 = 12.
Answer: Use equivalent operations on both sides. Correct solution: x = 12 − 7 = 5
06Compare two related cases and explain what changes and what stays mathematically consistent. Case A: Solve x + 9 = 15. Case B: Solve x + 3 = 9.
Answer: Case A: x = 15 − 9 = 6 Case B: x = 9 − 3 = 6
07Solve x + 3 = 10.
Answer: x = 10 − 3 = 7
08Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 13.
Answer: x = 13 − 5 = 8
Common mistakes
Learn to catch the error, not just the answer.
Use equivalent operations on both sides.
Only terms with the same variable part are like terms.
Applications & challenge
Use the idea beyond a single exercise.
Applications
- Translate cost, distance, rate, and measurement situations into symbolic rules.
- Use equations and inequalities to determine unknown quantities, thresholds, and feasible ranges.
Challenge problems
Explain why a valid method works, then solve: Solve x + 7 = 16.
x = 16 − 7 = 9
Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 19.
x = 19 − 9 = 10
Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 5.
x = 5 − 3 = 2
Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 8.
x = 8 − 5 = 3
Flashcards
Retrieve it from memory.
Flashcards
Card 1 of 4
Game mode
Grade 6 Chapter 4 Reasoning Lab
Solve solve one-step addition and subtraction equations problems accurately, choose an appropriate representation, and justify each result with a check.
Practice
Mastery check
01Error analysis: a student says, "Changing only one side of an equation." Explain the mistake, then solve this related task correctly: Solve x + 7 = 11.
Answer: Use equivalent operations on both sides. Correct solution: x = 11 − 7 = 4
02Compare two related cases and explain what changes and what stays mathematically consistent. Case A: Solve x + 9 = 14. Case B: Solve x + 3 = 8.
Answer: Case A: x = 14 − 9 = 5 Case B: x = 8 − 3 = 5
03Solve x + 3 = 9.
Answer: x = 9 − 3 = 6
04Represent before calculating. Use words, an expression or equation, a table, and when useful a graph for this task, then solve: Solve x + 5 = 12.
Answer: x = 12 − 5 = 7
05Explain why a valid method works, then solve: Solve x + 7 = 15.
Answer: x = 15 − 7 = 8
06Estimate or predict first, then calculate and decide whether the result is reasonable: Solve x + 9 = 18.
Answer: x = 18 − 9 = 9
07Solve and verify the result with a second method, inverse operation, or equivalent representation: Solve x + 3 = 13.
Answer: x = 13 − 3 = 10
08Interpret the answer in context after solving. What does the result mean here? Solve x + 5 = 7.
Answer: x = 7 − 5 = 2
Terminology
Words to know
- variable
- A symbol representing a number that may vary or be unknown.
- coefficient
- A numerical factor multiplying a variable.
- expression
- A combination of numbers, variables, and operations.
- solution
- A value that makes an equation or inequality true.
Continue learning
Connected concepts
Curriculum references
Standards and instructional references
Grade 6 scope, sequence, standards, and public task structure
Reference for coherent sequencing, representations, dependency-aware progression, and reasoning-rich task types.Eureka Math² Grade 6 program structure
Reference for module/topic coherence, recap, mixed-practice, and cumulative-learning patterns.enVision Mathematics Grade 6 instructional model
Reference for problem-based entry points, visual learning, modeling, and application patterns.Common Core State Standards for Mathematics — Grade 6
Grade-level content and mathematical-practice expectations.