Lesson 5.15.1 Small Group · Group 1
Start hereWords, worked example, and sentence starters
Learning target With my small group, I can find the area of a parallelogram using base × height — one step at a time, with support.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| Slanted sideSpanish: Lado inclinado | A side that leans instead of going straight up and down. It is not the perpendicular height. | In a leaning parallelogram, use the dashed 90° height—not the slanted side—in A = b × h. |
| ParallelogramSpanish: Paralelogramo | A four-sided shape with two pairs of parallel sides. | opposite sides never meet |
| ParallelSpanish: Paralelas | Two lines or sides that stay the same distance apart and never meet. | The top and bottom of a parallelogram never get closer together — matching arrowheads (›) mark one parallel pair, double arrowheads (››) mark the other. |
| BaseSpanish: Base | Any side of a parallelogram can be the base. Once you pick a base, the height must be measured perpendicular (at a 90° angle) to it. | b in A = b × h |
| HeightSpanish: Altura | The straight-up distance from the base to the top. | h in A = b × h |
| PerpendicularSpanish: Perpendicular | Two lines that meet to make a square corner (90 degrees). | height ⟂ base |
How it worksWorked examplefinding the area of a parallelogram
These numbers are not on your problems. The steps are. Follow them with your own numbers.
A parallelogram has a base of 14 cm. The perpendicular height to that base is 6 cm. Find the area.
- Write the formula. A = b × h
- Name the parts. base b = 14 cm perpendicular height h = 6 cm
- The slanted side is never the height — use the square-corner distance.
- Multiply and label square units. 14 × 6 = 84
Answer: The area of the parallelogram is 84 square centimeters (84 cm²).
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
A parallelogram has a base of 9 in. and a perpendicular height of 7 in. Find the area.
- Write the formula. A = ×
- Name the parts. base = in. height = in.
- Which measure makes a square corner with the base?
- Multiply. × = Units:
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
- The base is and the perpendicular height is .
- I know that measure is the height because .
- Area = × = square units.
- The slanted side is not used because .
Word bank parallelogrambaseheightperpendicularsquare cornerareaformulamultiplysquare unitsslanted siderectanglerearrange
Watch outA common mistake
The most common mistake in Area of Parallelograms is multiplying the base by the slanted side instead of the perpendicular height. For a parallelogram with a base of 16 ft, a perpendicular height of 9 ft, and a slanted side of 11 ft, students compute 16 × 11 = 176 square feet instead of the correct 16 × 9 = 144 square feet. The height must be the straight-up (perpendicular) distance between the base and its opposite side, not the length of the slanted side, even though the slanted side is often the number that 'looks' like it belongs in the formula.
Lesson 5.15.1 Small Group · Group 1
Group 1Supported practice
Learning target With my small group, I can find the area of a parallelogram using base × height — one step at a time, with support.
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1Complete each step, then write the final answer.
The dashed height meets the base at a square corner. A parallelogram has a base of 12 cm and a height of 7 cm. Find its area.
- 1What are the base and the height?
- 2Multiply the base by the height. What do you get?
- 3What units does the area use?
Final answer: -
2Complete each step, then write the final answer.
Two lengths go up: one is slanted, one is the height. A parallelogram has a base of 10 m, a height of 6 m and a slanted side of 8 m. Find its area.
- 1Which length is the height: 6 m or 8 m?
- 2Why is the 8 m side not the height?
- 3Multiply the base by the height. What is the area?
Final answer: -
3Complete each step, then write the final answer.
A parallelogram has a base of 7 inches and a height of 3 inches. Find its area.
Show your workHint Multiply the base by the height.
Final answer: -
4Complete each step, then write the final answer.
A parallelogram has a base of 16 feet and a height of 11 feet. Find its area.
Show your workHint Use A = b × h. You can break 16 × 11 into 16 × 10 and 16 × 1.
Final answer: -
5Complete each step, then write the final answer.
A park is shaped like a parallelogram. Its base is 30 yards. Its height is 20 yards. How many square yards of grass cover the park?
Show your workHint The grass covers the whole park. Find the area of the parallelogram.
Final answer: -
6Complete each step, then write the final answer.
Leo finds the area of a parallelogram. The base is 11 cm, the slanted side is 7 cm and the height is 5 cm. He writes 11 × 7 = 77. What is the correct area?
Show your workHint Leo used the wrong length. Which length meets the base at a square corner?
Final answer:
Explain your thinkingWhy do we use the height and not the slanted side? Use Leo’s mistake to explain.
Sentence starter The height is ___ because it meets the base at ___. · Leo got 77 because he ___.