🧠 WHY BOX — Why learn this?

Understanding this topic helps you solve real-life math problems and prepares you for the SSPA exam.

學好這個課題能幫助你解決生活數學問題,為 SSPA 考試做好準備。

📖 Story Context / 故事情境

Imagine you are shopping and need to calculate totals, discounts, or split bills. Math is everywhere in daily life!

想像你在購物時需要計算總額、折扣或分攤帳單。數學無處不在!

📋 Parent Corner / 家長專區
This topic covers key SSPA exam concepts. Encourage your child to practice the worked examples and common trap questions.
本課題涵蓋 SSPA 考試重點。請鼓勵孩子練習例題和陷阱題。
Primary 5 · Lesson 36 · Student Handout
SSPA Specialty - Geometry Questions Sprint for Full Score
T4 area + T5 volume/geometry · Two geometric traps total attack · 75 minutes · 1-to-3 Online Lesson
Corresponding textbooks:Scored test paper 1 + paper 2 geometry questions (accounting for about 25-35% of the paper) · Area · Volume · Combined figures
Core traps:🪤 T4 area formula trap · T5 geometry/volume trap —🔴 SSPA compulsory exam
SSPA association:🔴 High frequencyThe average score loss rate for geometry questions is 40%, formula confusion is the number one killer
Prerequisite knowledge:L3–L6 area (parallelogram · triangle · trapezoid · polygon)
Class goal:❶ Area formula muscle memory ❷ Zero confusion in volume calculations ❸ Combined graph segmentation strategies ❹ Correct unit conversion
Student Name: Class: Date: Time Spent:
═══════════════ PAGE 2: KP1 Area Trap Total Attack ═══════════════
I. Geometry warm-up (total 5 questions, 5 minutes)
🏆 SSPA衝刺·限時挑戰
模擬真實SSPA考試!限時作答,每題計分。答對率達80%解鎖「SSPA戰士」勳章!
⚡ 開始模擬考 →
#QuestionDifficultyWorking Space
W1Write the formula for the area of ​​a parallelogram.🌱
W2Write the formula for the area of ​​a triangle.🌱
W3Write the formula for the area of ​​a trapezoid.🌱
W4The rectangle is 8 cm long and 5 cm wide. Area = ? Perimeter = ?🌱
W5The side length of the square is 6 cm. Area = ? Perimeter = ?🌱
📐 Quick reference for geometric figures (this Lesson has/haveQuestiontotaluse)
Square A=a²
a
P=4a
Rectangle A=l×w
lw
P=2(l+w)
Triangle A=½bh
hb
High hem
isosceles triangle
hb
Both waists are equal and the height is on the inside
Trapezoid A=½(a+b)h
hb₂b₁
b₁=upper bottom·b₂=lower bottom
Circle A=πr²·C=2πr
Ord=2r
π≈3.14 or 22/7
⚠️ The most common mistakes in SSPA geometry questions: ① Confusing the area formula and the perimeter formula ② Forgetting ÷2 (triangle/trapezoid) ③ The height must be the vertical distance ④ Wrong writing of the unit (cm² vs cm)
II.Core Knowledge + Worked Examples
Knowledge Point 1: Area Trap Total Attack (T4 Area Formula) 🔴 SSPA required test
Five major area formulas (Must have muscle memory!):
① Area of square = side length × side length
② Area of rectangle = length × width
③ Area of parallelogram = base ×Height(Height is the vertical distance, not the hypotenuse!)
④ Area of triangle = base × height÷ 2(÷2 is easiest to forget!)
⑤ Area of trapezoid =(upper base + lower base) × height ÷ 2(not "add height and multiply by 2"!)
Unit trap:The area unit is cm²/m², not cm/m! The answer must be written in square units!
SVG 1: Ladder annotation diagram
Figure 1: Trapezoid area = (upper base + lower base) × height ÷ 2
Geometry trap example 1
Example KP1-1: Trapezoid area formula trap
The upper base of the trapezoid is 6 cm, the lower base is 10 cm, and the height is 4 cm. Area = ?
❌ Common mistakes
(6+10+4) ÷ 2 = 10 cm²
Add more height! The formula is (upper bottom + lower bottom) × height ÷ 2
✅ Correct solution
(6+10)×4÷2 = 32 cm²
First add the two bases = 16, × height = 64, ÷2 = 32
Example KP1-2: Height of parallelogram vs hypotenuse
The base of a parallelogram is 8 cm, the height is 5 cm, and the hypotenuse is 6 cm. Area = ?
❌ Common mistakes
8 × 6 = 48 cm²
Used a bevel! Area of ​​parallelogram = base × height (vertical distance)
✅ Correct solution
8 × 5 = 40 cm²
Height = vertical distance = 5 cm, not hypotenuse 6 cm
🧠 Tip: "Multiply the height of a flat base by multiplying it, divide a triangle by two, add two bases of a trapezoid, multiply the height by dividing by two, and use the hypotenuse as a trap."
⚠️ The three most common mistakes in T4: (1) Forgetting ÷2 for triangles (2) Using the hypotenuse for parallelograms (3) Recording the trapezoid formula as (upper base + lower base + height) × 2
KP1 Synchronization practice — areacalculate (question 1-15)
#QuestionDifficultyWorking Space
1The parallelogram has a base of 12 cm and a height of 7 cm. Area = ?🌱
2Triangular base 10 cm, height 6 cm. Area = ? (Did you divide by 2?)🌱
3The upper base of the trapezoid is 5 cm, the lower base is 9 cm, and the height is 6 cm. Area = ?🌱
4The rectangle is 15 cm long and 8 cm wide. Area = ? Perimeter = ?🌱
5The side length of the square is 9 cm. Area = ?🌱
6The parallelogram has a base of 20 cm, a height of 8 cm, and a hypotenuse of 10 cm. Area = ?🌿
7Triangular base 14 cm, height 9 cm. Area = ?🌿
8The upper base of the trapezoid is 7 cm, the lower base is 13 cm, and the height is 5 cm. Area = ?🌿
9The parallelogram has a base of 3.5 cm and a height of 2 cm. Area = ?🌿
10The area of ​​the triangle is 24 cm² and the base is 8 cm. How high is it?🌳
11The area of ​​a trapezoid is 40 cm², its upper base is 5 cm, and its lower base is 11 cm. How high is it?🌳
12A parallelogram and a triangle have the same base and height. The area of ​​the triangle is 18 cm². Area of ​​parallelogram = ?🌳
13The base of the triangle is 16 cm and the height is half the base. Area = ?🌳
14A parallelogram has an area of ​​72 cm² and a height of 8 cm. bottom = ? (Note: not the hypotenuse!)🌳
15Two identical trapezoids form a parallelogram. Each trapezoid has an upper base of 4 cm, a lower base of 10 cm, and a height of 6 cm. The area of ​​the parallelogram = ?🌳
═══════════════ PAGE 3: KP2 Volume Trap Total Attack ═══════════════
Knowledge Point 2: Volume Trap Total Attack (T5 Geometry/Volume) 🔴 SSPA required test
Core formulas and traps of volume:
① Volume of cuboid = length × width × height
② Volume of cube = side length × side length × side length (cube of side length)
Unit trap |||SEP|||: The volume unit is cm³/m³ (cubic), not cm² (square)!Capacity conversion
Surface area vs volume confusion |||SEP|||: Surface area = sum of the areas of all faces (unit cm²), volume = length × width × height (unit cm³):1 cm³ = 1 mL,1000 cm³ = 1 L
Surface area vs volume confusion: Surface area = sum of the areas of all faces (unit cm²), volume = length × width × height (unit cm³)
SVG 2: Cuboid stereogram
Figure 2: Volume of cuboid = length × width × height (unit: cm³)
Cuboid volume diagram
Example KP2-1: Volume vs surface area confusion
A cuboid is 5 cm long, 4 cm wide and 3 cm high. Find (a) volume (b) surface area.
❌ Common mistakes
Volume = surface area = 5×4=20
Confusing volume and surface area with wrong units
✅ Correct solution
Volume = 5×4×3 = 60 cm³
Surface area = 2(5×4+5×3+4×3)
= 2(20+15+12) = 94 cm²
The volume is cubic (×3 times), and the surface area is the sum of the areas of the six sides
Example KP2-2: Capacity conversion trap
A water tank is 20 cm long, 15 cm wide and 10 cm high. How many liters of water can be filled?
❌ Common mistakes
20×15×10 = 3000 L
3000 cm³ ≠ 3000 L!1 L = 1000 cm³
✅ Correct solution
Volume = 20×15×10 = 3000 cm³
= 3000 ÷ 1000 = 3 L
cm³ to L to ÷1000
⚠️ T5 must remember: 1 cm³ = 1 mL, 1000 cm³ = 1 L. The unit of volume is "cubic" not "square"!
KP2 synchronization practice — volume and table area (question 16-28)
#QuestionDifficultyWorking Space
16The cuboid is 6 cm long, 4 cm wide and 2 cm high. Volume = ?🌱
17The side length of the cube is 5 cm. Volume = ?🌱
18The cuboid is 10 cm long, 5 cm wide and 3 cm high. (a) Volume = ? (b) Surface area = ?🌿
19The inside of the tank is 30 cm long, 20 cm wide, and 15 cm deep. Volume of water = ? How many liters?🌿
20The surface area of ​​the cube is 150 cm². Side length = ? Volume = ?🌳
21The volume of a cuboid is 240 cm³, its length is 10 cm and its width is 6 cm. High = ?🌿
22A fish tank is 40 cm long, 25 cm wide, and 30 cm high. How many liters of water can be filled? (1 L = 1000 cm³)🌿
23The side length of the cube is 8 cm. Surface area = ? Volume = ? (Note that the units are different!)🌿
24The sum of the lengths of all sides of a cuboid is 48 cm. 6 cm long, 4 cm wide. High = ? Volume = ?🌳
25The volume of a cube is 512 cm³. Side length = ? Surface area = ?🌳
26The original water in the water tank is 5 L. After a stone is placed, the water level rises and the volume becomes 5.8 L. What is the volume of the stone in cm³?🌳
27The length of a cuboid is 8 cm, its width is half its length, and its height is twice its width. Volume = ?🏔️
28Cut a cube with side length 10 cm into 8 identical small cubes. Volume of each small cube = ? Side length = ?🏔️
═══════════════ PAGE 4: KP3 Combination Graphics Strategy ═══════════════
Knowledge Point 3: Combination Graphics Strategy (T4 + T5 Comprehensive) 🔴 SSPA Required Exam
Three-step method for solving combined graphics problems:
Divide |||SEP|||: Split the combined graphics into basic graphics (rectangle, triangle, trapezoid, parallelogram)Mark the dimensions |||SEP|||: Mark the required base, height, length, and width for each basic graphics (note that some dimensions need to be calculated)
Calculate separately and then merge: Add (merge graphics), subtract (hollow out graphics)
Volume combination: Divide into multiple cuboids/cubes first, find the volumes separately and then add them up
Overlap trap: When two graphics overlap, do not repeat calculations!
overlap trap: When two graphics overlap, do not repeat calculations!
SVG 3: Combined graphics (rectangle + triangle)
Figure 3: Combined shape = rectangle + triangle (division method)
Geometry trap example 2
Example question KP3-1: Area of ​​combined graphics (refer to Figure 3)
Find the total area of ​​the combined shapes in Figure 3. Rectangle 12×8, triangle base 10 and height 6.
❌ Common mistakes
12×8 + 10×6 = 96+60 = 156 cm²
Triangle Forgot ÷2!
✅ Correct solution
A = 12×8 = 96 cm²
B = 10×6÷2 = 30 cm²
Total = 126 cm²
Use the correct formula for each basic graph
Example KP3-2: Combined volume (superposition of two cuboids)
An L-shaped object consists of two cuboids: a lower cuboid 10×5×4 cm and an upper cuboid 6×5×3 cm stacked at the lower end. Total volume = ?
❌ Common mistakes
10×5×4 + 6×5×3 = 200+90 = 290 cm³
It seems correct, but if the two cuboids overlap, they need to be subtracted.
✅ Correct solution
V₁ = 10×5×4 = 200 cm³
V₂ = 6×5×3 = 90 cm³
Total = 290 cm³ (without overlap)
Calculate the volumes separately and add them after confirming there is no overlap.
⚠️ The most frequent errors in combined graphics: (1) Forgetting ÷2 for triangles (2) Forgetting to calculate the "hidden size" (3) Repeating calculations for overlapping parts
KP3 synchronization practice — compound shape (question 29-40)
#QuestionDifficultyWorking Space
29A composite figure consists of a rectangle (8 × 5 cm) and a triangle (base 8 cm, height 4 cm). Total area = ?🌿
30Cut out a triangle (base 6 cm, height 4 cm) in a rectangle (10×6 cm). Remaining area = ?🌿
31A trapezoid (upper base 4 cm, lower base 10 cm, height 6 cm) is topped by a triangle (base 10 cm, height 3 cm). Total area = ?🌳
32Two identical parallelograms (base 8 cm, height 5 cm) are put together to overlap a triangle (base 8 cm, height 2.5 cm). Total area = ?🌳
33An L-shaped plane consists of two rectangles: 12×4 cm vertically and 8×5 cm horizontally. They overlap a 4 × 4 cm square. Total area = ?🏔️
34
10x5x210x5x210x5x23 steps stairs
A stair-shaped volume consists of 3 levels. Each level is 10 cm long, 5 cm wide and 2 cm high. Three levels are stacked to form a ladder. Total volume = ?
🌳
35Cut a trapezoid (upper base 4 cm, lower base 8 cm, height 5 cm) out of a rectangle (15×10 cm). Remaining area = ?🌳
36A small cuboid (4×3×2 cm) is dug out of a large cuboid (10×8×6 cm). Remaining volume = ?🌳
37A square has a side of 10 cm and is cut diagonally into two triangles. Area of ​​each triangle = ?🌿
38Two identical trapezoids (upper base 3 cm, lower base 7 cm, height 4 cm) are assembled into a hexagon "bottom to bottom". Total area = ?🌳
39A rectangular park 50 m × 30 m. There is a straight path 2 m wide in the middle that runs through the long sides. Usable grass area = ?🏔️
40The cube has a side length of 6 cm. The surface is painted and then cut into 27 small cubes with a side length of 2 cm. How many small cubes are there with "paint on one side"?🏔️
III. Geometry Ultimate Sprint (question 41-45 · 🚀 champion level challenge)
#QuestionDifficultyWorking Space
41A hexagon can be divided into a rectangle (8×6 cm) and two identical triangles (each base 4 cm and height 6 cm). Area of ​​hexagon = ?🌳
42If the side length of a cube is doubled, how many times its volume will increase? How many times does the surface area change?🏔️
43
Rectangle
12
Parallelogram
h=5Bottom=12
A rectangle and a parallelogram have equal bases and equal heights (base 12 cm, height 5 cm). What is the difference between the areas of the two shapes? Why?
🏔️
44
20x10x8 (bottom layer)Cube4x4x4
A combined solid: a cuboid (20×10×8 cm) below and a cube (side length 4 cm) above in the center. Total volume = ? Surface area = ? (Note: The joint surface does not count as surface area)
🏔️
45Draw an irregular shape on graph paper (1 cm² per square). There are 24 complete squares, and about 8 half squares and most half squares. Estimated area = ? Write out your estimation method.🏔️
IV.areaformula cheat sheet
graphicsareaformulamostCommon Mistake
squareside length × side lengthconfused with perimeter
rectanglelength × widthconfused with perimeter
parallelogramBottom ×highUse hypotenuse as height
trianglebottom × height÷ 2forget ÷2
trapezoid(upper bottom + lower bottom) × height ÷ 2Add height / forget ÷2
V. The Lessoncorecommon errorsummary
🎯 Review of Learning Objectives - After completing this lesson you should be able to:
☐ Identify all trap types in our hall ☐ Solve 🌱basic questions independently (100% correct) ☐ Challenge🌿Advanced questions (80%+ correct) ☐ Explain the lesson formula to classmates
#common errortrapCorrect Approach
1Forget the area of ​​a triangle ÷2T4Remember: base × height is a parallelogram, and a triangle only needs half
2Parallelogram uses hypotenuseT4The height must be the vertical distance, and the hypotenuse must be the interference item
3Add height to the trapezoidal formulaT4The formula is (upper + lower) × height ÷ 2, not (upper + lower + height) × 2
4Area vs perimeter confusionT4Perimeter = sum of side lengths (cm), area = calculated by formula (cm²)
5Volume vs surface area confusionT5Volume = cm³ (space occupied), surface area = cm² (sum of six side areas)
6Capacity conversion errorT51 cm³ = 1 mL, 1000 cm³ = 1 L, must ÷1000
7Combined graphics overlap and repeat calculationsT4/T5After segmentation, check whether there is overlap. If there is overlap, you must subtract it once.
8Area/volume unit spelled incorrectlyT4/T5The area must be written in cm²/m² and the volume must be written in cm³/m³
9Hidden dimensions are not calculatedT4/T5Some dimensions are not given directly and need to be inferred from other known dimensions.
Strategies for getting perfect marks on geometry questions in sub-tests 🔴 Must read
Three-step verification method for geometry questions:
Formula check |||SEP|||: Write the formula → Substitute the numbers → Confirm ÷2 / Not ÷2Unit check
: Area → cm²/m², volume → cm³/m³, length → cm/mReasonability check
: For example, the area of a triangle < the area of a parallelogram with the same base and the same height? Is the area of ​​the trapezoid reasonable?: For example, the area of ​​a triangle < the area of ​​a parallelogram with the same base and the same height? Is the area of ​​the trapezoid reasonable?
🧠 Tips for perfect score in geometry: "Recite formulas for area, divide triangles by two, use height instead of slant for squares, volume is cubic, and units must be understood clearly."
Lam Fung Academy · LF Academy · We don't teach math. We teach trap avoidance.
Print Ctrl+P PDF | 6 pages · 55 questions | LF-P5-S1-L36 v6 EN
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