6.GR.1 Lesson 5-3-group1 🟡 Group 1 · Set B
MASTERY CHECK
☐ Exceeds☐ Meets Target☐ Needs Practice

5.3 Small Group · Group 1

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

Area of Trapezoids · Trapezoid · Procedural Fluency · Real-World Applications

Interactive Workbench & Models →
Name: Date: Period: Learning Goal:
■ CONCEPT SUMMARY & GUIDED NOTES: Let's build it together — How do we find the area of a trapezoid?
1Area of a trapezoid = ½ × (base 1 + base 2) × height. We add the two bases first, then take half.
  • A trapezoid is a four-sided shape with one pair of parallel sides. The two parallel sides are called the bases, and they have different lengths. 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. My trapezoid window has a top base of 4 feet, a bottom base of 8 feet, and a height of 5 feet.
  2. I write the formula: A = ½ × (b1 + b2) × h.
  3. I add the bases first: 4 + 8 = 12.
  4. I multiply by the height: 12 × 5 = 60.
  5. I take half: ½ × 60 = 30. So the area is 30 square feet.
3Mathematical Word Bank
  • Area of Trapezoids (Área de trapecios) — The space inside a trapezoid. Formula: A = 1/2(b₁ + b₂)h.
  • Trapezoid (Trapecio) — A four-sided shape with just one pair of parallel sides.
  • Parallel (Paralelas) — Two lines or sides that stay the same distance apart and never meet.
  • Base 1 (b1) (Base 1 (b1)) — One of the two parallel sides of a trapezoid.
  • Base 2 (b2) (Base 2 (b2)) — The other parallel side of a trapezoid.
  • Height (Altura) — The straight-up distance between the two parallel sides.
4Watch out
  • A common mistake in Area of Trapezoids is forgetting the ½ in A = ½ × (b1 + b2) × h. After adding the bases and multiplying by the height, students stop there instead of taking half — for example, with bases 6 ft and 10 ft and a height of 4 ft, they compute (6 + 10) × 4 = 64 sq ft instead of taking half to get the correct 32 sq ft. That unhalved number is really the area of the parallelogram made from two trapezoids, not the area of one trapezoid. Before you submit, always ask: "Did I take half of my last answer?"
SECTION 1 REAL-WORLD CONTEXTS & PROBLEM SOLVING [Applications]
  1. 1 MULTIPLE CHOICE

    Blueprint 1: A trapezoidal lobby window has bases of 6 ft and 10 ft and a height of 4 ft. What is its area for the glass order?

    1. A32 sq ft
    2. B40 sq ft
    3. C16 sq ft
    4. D60 sq ft
    Formula
    Put the numbers in
    Work it out
    Answer with its unit
    1. 1Name itWhich measure is asked?
    2. 2Write the formulaBefore any numbers.
    3. 3SubstituteMatch each letter.
    4. 4Unitunits, sq units, or cubic?
  2. 2 MULTIPLE CHOICE

    Blueprint 2: A trapezoidal skylight has bases of 9 ft and 7 ft and a height of 6 ft. What is its area?

    1. A48 sq ft
    2. B96 sq ft
    3. C63 sq ft
    4. D44 sq ft
    Formula
    Put the numbers in
    Work it out
    Answer with its unit
    1. 1Name itWhich measure is asked?
    2. 2Write the formulaBefore any numbers.
    3. 3SubstituteMatch each letter.
    4. 4Unitunits, sq units, or cubic?
  3. 3 MULTIPLE CHOICE

    Two equal trapezoid windows join to form a parallelogram with area 96 sq ft. What is the area of ONE trapezoid?

    1. A48 sq ft
    2. B96 sq ft
    3. C16 sq ft
    4. D192 sq ft
    Formula
    Put the numbers in
    Work it out
    Answer with its unit
    1. 1Name itWhich measure is asked?
    2. 2Write the formulaBefore any numbers.
    3. 3SubstituteMatch each letter.
    4. 4Unitunits, sq units, or cubic?
SECTION 2 MATHEMATICAL WRITING & ERROR ANALYSIS [Reasoning & Critique]
  1. 4 ERROR ANALYSIS

    Find the Missing Half

    1. 1Read the blueprint:A trapezoid-shaped patio stone has b1 = 4 ft, b2 = 8 ft, and h = 6 ft.
    2. 2Write the formula:A = ½ × (b1 + b2) × h
    3. 3Add the bases, then multiply by height:(4 + 8) × 6 = 12 × 6 = 72
    4. 4State the area:A = 72 sq ft

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

    ✏️ Corrected Mathematical Work & Explanation
  2. 5 ERROR ANALYSIS

    Using the Wrong Height

    1. 1Read the blueprint:A trapezoid window has b1 = 7 ft and b2 = 13 ft. The slanted side measures 10 ft, and the straight-up height between the bases is 6 ft.
    2. 2Write the formula:A = ½ × (b1 + b2) × h
    3. 3Substitute values:A = ½ × (7 + 13) × 10
    4. 4Calculate:A = ½ × 20 × 10 = 100 sq ft

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

    ✏️ Corrected Mathematical Work & Explanation
  3. 6 ERROR ANALYSIS

    Level 2 Extension — The Missing Half

    1. 1Read the blueprint:Trapezoid window: b1 = 6 ft, b2 = 10 ft, h = 4 ft
    2. 2Write the formula:A = ½ × (b1 + b2) × h
    3. 3Add the bases, then multiply by height:(6 + 10) × 4 = 16 × 4 = 64
    4. 4State the area for the glass order:A = 64 sq ft

    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