Area of Polygons — measure, build, and prove every shape!
45 min class: Steps 1–3 (~15 min) → Self-Check (~10 min) → Steps 4–5 + Final Quiz (~20 min). 60 min class: add pair-share after each formula step and debrief the composite figure with the whole group.
Best used in pairs for Steps 1–4 so students can talk through the cutting strategy for composite figures. Step 5 (final quiz) should be completed individually.
Welcome, Area Architect! 🏗️ A new park needs floor plans, and you are the math behind the build.
Area is the number of unit squares that fit inside a flat shape. We measure it in square units (like cm² or ft²). In this WebQuest you will find the area of parallelograms, triangles, trapezoids, and composite figures (shapes made of smaller shapes).
By the end, you will be able to:
Do the steps in order. Read each one carefully.
Area = space inside a flat shape. Base and height must meet at a right angle (a square corner). For a parallelogram the height is the perpendicular distance between the two bases — not the slanted side.
Open the Area Architect 3D game. Build blocks to match the gold target area. Watch how base × height fills the parallelogram.
An L-shaped room splits into two rectangles (rectangles are special parallelograms). Find each area, then add them together.
Complete the Self-Check below, then type your name in the bar above, finish the final quiz, and Save as PDF or DOC to turn in.
Use these to help you:
Answer each question, then press Check to see if you are right. Read the explanation before moving on.
SC1. A parallelogram has a base of 7 cm and a height of 4 cm. What is its area?
Use A = b × h. Type a number.SC2. A triangle has a base of 10 m and a height of 6 m. What is its area?
Use A = ½ × b × h. Type a number.SC3. A trapezoid has bases of 5 ft and 9 ft and a height of 4 ft. What is its area?
Use A = ½ × (b₁ + b₂) × h. Type a number.SC4. An L-shaped floor is made of two rectangles: one is 6 m × 3 m and the other is 4 m × 2 m. What is the total area?
Find each rectangle's area, then add. Type a number.| Skill | 4 — Expert | 3 — Good | 2 — Getting there | 1 — Keep trying |
|---|---|---|---|---|
| Parallelogram & rectangle area | Applies A = b × h correctly every time, including slanted sides. | Applies A = b × h correctly most of the time. | Uses the formula with occasional errors. | Needs support to use the formula. |
| Triangle area | Uses A = ½bh quickly and correctly every time. | Uses the triangle formula correctly. | Uses the formula with help or minor errors. | Triangle area formula not yet mastered. |
| Trapezoid area | Identifies both bases and height, applies formula correctly every time. | Applies the trapezoid formula correctly. | Applies the formula with prompting. | Has difficulty identifying the two bases. |
| Composite figures | Splits any composite figure and adds parts with no errors. | Splits and adds parts with few errors. | Finds some parts correctly with guidance. | Cannot yet split the shape independently. |
Great work, Area Architect! You can now find the area of parallelograms, triangles, trapezoids, and composite figures. These same skills help you plan rooms, gardens, sports fields, and floor plans. Complete the reflection and final quiz below to show what you learned.
Answer these two questions in your own words before you submit.
1. Which shape was hardest for you — parallelogram, triangle, or trapezoid? Why?
2. Describe one real-life situation where you would need to calculate area.
Answer all 6. Then press Check My Answers. Type numbers only when asked.
Your score and a ✓/✗ for each question will appear in the panel at the top. Then use Save as PDF or Save as DOC to turn it in.
Share with students only after submission. Keep collapsed during student work time.
| Item | Correct Answer | Formula / Work |
|---|---|---|
| SC1 | 28 cm² | b × h = 7 × 4 = 28 |
| SC2 | 30 m² | ½ × 10 × 6 = 30 |
| SC3 | 28 ft² | ½ × (5+9) × 4 = ½ × 14 × 4 = 28 |
| SC4 | 26 m² | 6×3 + 4×2 = 18 + 8 = 26 |
| Q1 | 40 cm² | 8 × 5 = 40 |
| Q2 | 20 cm² | ½ × 10 × 4 = 20 |
| Q3 | 36 ft² | 6 × 6 = 36 |
| Q4 | 20 m² | 12 + 8 = 20 |
| Q5 | square units | Area is always in square units |
| Q6 | 32 in² | ½ × (6+10) × 4 = ½ × 16 × 4 = 32 |