Determine the Area of Parallelograms and Rhombuses

Derive and apply area formulas for parallelograms (A = bh) and rhombuses (A = d₁ × d₂ ÷ 2).

6.GR.A.1 · Area, Surface Area & Volume
Level
Guided practice with vocabulary support

🟠 Level 0 — Extra Support

Sentence starters: “First, I…” · “The answer is… because…” · “I know this because…”
W

Warm-Up

2 questions
Warm-Up 1
Which measurement do you need to find the area of a parallelogram?
Vocabulary: A parallelogram is a four-sided shape with two pairs of parallel sides. To find its area, you need the base and the height (the perpendicular distance between the bases).
base (b) height (h)
✓Correct! The area of a parallelogram uses the formula A = base × height.
✗Not quite. To find the area of a parallelogram, you need the base and the perpendicular height. A = b × h. The answer is A.
Warm-Up 2
A parallelogram has a base of 10 cm and a height of 6 cm. What is its area?
Formula: A = b × h. Multiply the base by the height.
✓Correct! A = 10 × 6 = 60 cm².
✗Use A = b × h. That gives 10 × 6 = 60 cm². The answer is C.
P

Practice

5 questions
Practice 1
Find the area of the parallelogram below.
Remember: Area = base × height. Use the perpendicular height, not the slant side.
14 in. 8 in. 10 in.
A = in.²
Show your work:

Sentence frame: "The area is ___ × ___ = ___ square inches."

✓Correct! A = 14 × 8 = 112 in.². Remember to use the height (8 in.), not the slant side (10 in.).
✗Use the base (14 in.) and the height (8 in.), not the slant side. A = 14 × 8 = 112 in.².
Practice 2
A rhombus has diagonals of 12 m and 8 m. What is its area?
Vocabulary: A rhombus has four equal sides and its diagonals cross at right angles. Area = (d₁ × d₂) ÷ 2.
12 m 8 m
Explain your reasoning:

Sentence frame: "The diagonals are ___ and ___. A = (___ × ___) ÷ 2 = ___."

✓Correct! A = (12 × 8) ÷ 2 = 96 ÷ 2 = 48 m².
✗Use A = (d₁ × d₂) ÷ 2. A = (12 × 8) ÷ 2 = 96 ÷ 2 = 48 m². The answer is B.
Practice 3
Sort each formula to the correct shape.
Remember: Parallelogram: A = base × height. Rhombus: A = (d₁ × d₂) ÷ 2. A rectangle is a special parallelogram, so A = l × w.
A = b × h
A = (d₁ × d₂) ÷ 2
A = 9 × 5 = 45
A = (6 × 10) ÷ 2 = 30
A = 12 × 7 = 84
A = (8 × 14) ÷ 2 = 56
Parallelogram
Rhombus
✓All correct! Parallelogram uses A = bh. Rhombus uses A = (d₁ × d₂) ÷ 2.
✗Some items are in the wrong group. Parallelogram formulas use base × height. Rhombus formulas use diagonals. Try again!
Practice 4
A parallelogram has an area of 72 ft² and a base of 9 ft. What is its height?
Strategy: Use A = b × h. You know A and b, so solve for h: h = A ÷ b.
h = ft
Show your work:

Sentence frame: "Since A = b × h, I can find h = A ÷ b = ___ ÷ ___ = ___."

✓Correct! h = 72 ÷ 9 = 8 ft.
✗Use h = A ÷ b = 72 ÷ 9 = 8 ft.
Practice 5
Mr. Neft is designing a parallelogram-shaped garden plot with a base of 15 ft and a height of 8 ft. How many square feet of soil does he need to cover the entire garden?
Real-world connection: The garden is shaped like a parallelogram. Use A = b × h to find how much soil is needed.
Explain your answer:

Sentence frame: "Mr. Neft needs ___ square feet of soil because A = ___ × ___ = ___."

✓Correct! A = 15 × 8 = 120 ft². Mr. Neft needs 120 square feet of soil.
✗Use A = b × h = 15 × 8 = 120 ft². The answer is C.
★

Challenge

1 question
Challenge
A rhombus-shaped tile has an area of 54 cm². One diagonal is 9 cm long. What is the length of the other diagonal?
Think about it: Use A = (d₁ × d₂) ÷ 2. You know A = 54 and d₁ = 9. Solve for d₂.
d₂ = cm
Show your work step by step:

Sentence frame: "I used A = (d₁ × d₂) ÷ 2. Substituting: 54 = (9 × d₂) ÷ 2. So d₂ = ___."

✓Excellent! 54 = (9 × d₂) ÷ 2 → 108 = 9 × d₂ → d₂ = 12 cm.
✗54 = (9 × d₂) ÷ 2. Multiply both sides by 2: 108 = 9 × d₂. Divide: d₂ = 108 ÷ 9 = 12 cm.