Lesson 5.35.3 Small Group · Group 1
Start hereWords, worked example, and sentence starters
Learning target With my small group, I can find the area of a trapezoid using the formula A = ½(b1 + b2) × h — one step at a time, with support.
Why This Matters This is your support small group for Lesson 5.3. We're going to slow this down and build it together, one step at a time. You can ask a question any time — that's what this group is for.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| TrapezoidSpanish: Trapecio | A four-sided shape with just one pair of parallel sides. | top base and bottom base |
| ParallelSpanish: Paralelas | Two lines or sides that stay the same distance apart and never meet. | the two bases |
| Base 1 (b1)Spanish: Base 1 (b1) | One of the two parallel sides of a trapezoid. | If the bottom of the trapezoid is 10 ft, then b₁ = 10 ft in the formula A = ½(b₁ + b₂) × h |
| Base 2 (b2)Spanish: Base 2 (b2) | The other parallel side of a trapezoid. | If the top of the trapezoid is 6 ft, then b₂ = 6 ft; both bases are parallel to each other |
| HeightSpanish: Altura | The straight-up distance between the two parallel sides. | h, meets bases squarely |
| PerpendicularSpanish: Perpendicular | Two lines that meet to make a square corner (90 degrees). | The dashed height meets the base at a square corner — the small 90° box is what makes it perpendicular, not slanted. |
How it worksWorked example
These numbers are not on your problems. The steps are. Follow them with your own numbers.
Bases 6 cm and 14 cm, height 5 cm, two matching triangles.
- Rectangle: 6 × 5 = 30 cm².
- Each triangle base: (14 − 6) ÷ 2 = 4 cm.
- Triangles: 2 × (½ × 4 × 5) = 20 cm².
Answer: 30 + 20 = 50 cm²
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
A trapezoid has bases of 3 cm and 5 cm. Its height is 2 cm. Find its area.
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
- The two parallel bases are and .
- I decomposed the trapezoid into and .
- The pieces have areas , , and .
- The total area is square units because .
Word bank trapezoidparallelbaseheightdecomposerectangletriangleleftoveraddtotalareasquare units
Watch out!A common mistake
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
Lesson 5.35.3 Small Group · Group 1
Group 1Supported practice
Learning target With my small group, I can find the area of a trapezoid using the formula A = ½(b1 + b2) × h — one step at a time, with support.
Why This Matters This is your support small group for Lesson 5.3. We're going to slow this down and build it together, one step at a time. You can ask a question any time — that's what this group is for.
-
1Complete each step, then write the final answer.
The two bases are parallel. The height connects them. A trapezoid has bases of 6 cm and 9 cm. Its height is 4 cm. Find its area.
- 1Add the two bases. What do you get?
- 2Multiply the sum by the height.
- 3Take half. What is the area?
Final answer: -
2Complete each step, then write the final answer.
The slanted sides are not bases and not the height. A trapezoid has bases of 5 m and 11 m and a height of 4 m. Each slanted side is 5 m. Find its area.
- 1Which sides are the bases? Which length is the height?
- 2Add the bases. Multiply by the height.
- 3Take half. What is the area?
Final answer: -
3Complete each step, then write the final answer.
A trapezoid has bases of 2 in and 4 in. Its height is 3 in. Find its area.
Show your workHint Add the bases. Multiply by the height. Then take half.
Final answer: -
4Complete each step, then write the final answer.
A trapezoid has bases of 12 ft and 8 ft. Its height is 7 ft. Find its area.
Show your workHint Add the bases first. Then multiply by 7 and take half.
Final answer: -
5Complete each step, then write the final answer.
A garden bed is a trapezoid. Its parallel sides are 10 m and 14 m long. They are 5 m apart. What is the area of the garden bed?
Show your workHint The parallel sides are the bases. The distance between them is the height.
Final answer: -
6Complete each step, then write the final answer.
Rosa finds the area of a trapezoid with bases 7 cm and 3 cm and height 6 cm. She writes 7 × 6 = 42. What is the correct area?
Show your workHint Rosa used only one base. A trapezoid has two bases.
Final answer:
Explain your thinkingWhy do we add both bases before we multiply? Use Rosa’s mistake to explain.
Sentence starter A trapezoid has ___ bases, so we ___. · Rosa got 42 because she ___.