6.AT.8 Lesson 8-2-group1 🟡 Group 1 · Set B
MASTERY CHECK
☐ Exceeds☐ Meets Target☐ Needs Practice

8.2 Small Group · Group 1

Second Practice Form · Re-Teach, Homework or Retake · Same Standard, New Problems

Visual Models · Solve One-Step Addition and Subtraction Equations · Equation · Procedural Fluency

Interactive Workbench & Models →
Name: Date: Period: Learning Goal:
■ CONCEPT SUMMARY & GUIDED NOTES: Let's build it together — How do I solve an addition or subtraction equation?
1Undo the operation with its inverse, and do it to both sides to keep the equation balanced.
  • To solve means to find the value that makes the equation true. I use the inverse operation (the opposite) to get the variable alone, and I do the same thing to both sides. We'll walk through a worked example, try one together, then you'll try a few with hints right there when you need them.
2Worked Example — Watch me
  1. Solve n + 23 = 58. The 23 is added to n.
  2. The inverse of adding 23 is subtracting 23.
  3. I subtract 23 from both sides: n + 23 − 23 = 58 − 23.
  4. That leaves n = 35. Check: 35 + 23 = 58. True!
3Mathematical Word Bank
  • Solve One-Step Addition and Subtraction Equations (Resolver ecuaciones de suma y resta de un paso) — Use one inverse addition or subtraction operation to isolate the variable.
  • Equation (Ecuación) — A math sentence with an equal sign showing both sides are the same.
  • Inverse operation (Operación inversa) — Two math actions that undo each other, like × and ÷.
  • Isolate (Despejar) — To get the letter by itself on one side.
  • Solution (Solución) — A number that makes the equation or inequality true.
  • One-step equation (Ecuación de un paso) — An equation you can solve in a single step using one inverse operation.
4Watch out
  • A common mistake is applying the same operation instead of the inverse — for example, solving x − 7 = 15 by subtracting 7 from both sides (getting the wrong x = 8) instead of adding 7 to both sides (the correct x = 22). Another common mistake is doing the inverse operation to only one side, like solving x + 6 = 14 by subtracting 6 from the left but forgetting the right side. Before you submit, name the operation shown in the equation, choose its inverse, apply it to BOTH sides, and check by substituting your answer back into the original equation.
SECTION 1 REAL-WORLD CONTEXTS & PROBLEM SOLVING [Applications]
  1. 1 MULTIPLE CHOICE

    A shirt costs $d. After a $15 discount, it costs $38. What is d?

    1. A$53
    2. B$23
    3. C$38
    4. D$45
    ✏️ Workspace & Solution Steps
  2. 2 MULTIPLE CHOICE

    Unlock Card 1: Solve x + 7 = 15.

    1. Ax = 8
    2. Bx = 22
    3. Cx = 7
    4. Dx = 105
    ✏️ Workspace & Solution Steps
  3. 3 MULTIPLE CHOICE

    Unlock Card 2: Solve n − 4 = 9.

    1. An = 13
    2. Bn = 5
    3. Cn = 36
    4. Dn = -5
    ✏️ Workspace & Solution Steps
  4. 4 MULTIPLE CHOICE

    Unlock Card 3: A vault held some clue tokens. After the detective added 16 tokens, there were 50. The equation is t + 16 = 50. How many tokens were there before?

    1. A34
    2. B66
    3. C16
    4. D800
    My work — one step per lineWhat I did to both sides
    1. 1LookWhat is done to the variable?
    2. 2UndoDo the opposite — both sides.
    3. 3SimplifyOne side at a time.
    4. 4CheckPut it back in.
SECTION 2 MATHEMATICAL WRITING & ERROR ANALYSIS [Reasoning & Critique]
  1. 5 ERROR ANALYSIS

    Spot the Common Mistake

    1. 1Equation:x + 6 = 14
    2. 2Choose inverse:The inverse of + 6 is − 6.
    3. 3Subtract from one side only:x + 6 − 6 = 14, so x = 14

    Which step contains the error? Explain the mathematical misconception and write the correct calculation below.

    ✏️ Corrected Mathematical Work & Explanation
  2. 6 ERROR ANALYSIS

    Level 2 Extension — Crack the Detective's Mistake

    1. 1Equation:x + 8 = 21
    2. 2Choose inverse:Undo the + 8
    3. 3Apply to both sides:x + 8 + 8 = 21 + 8
    4. 4Simplify:x = 29

    Which step contains the error? Explain the mathematical misconception and write the correct calculation below.

    ✏️ Corrected Mathematical Work & Explanation
📐 CER MATHEMATICAL PROOF MATRIX (CER 2.0) SMP.3 / Proof & Justification

Writing Task: Justify why your mathematical solution is accurate and complete.

C Claim
Starter: My mathematical claim is that the solution is...
E Evidence
Starter: The evidence from the model/table demonstrates that...
R Reasoning
Starter: This proves my answer because the standard mathematical definition of...
Student Mastery Self-Assessment:
1 · Need More Support
2 · Getting Closer
3 · Got It / Solid
4 · Master / Can Teach It