PSLE Math Hub

Master the Syllabus & Conquer the Exam

Numbers & Algebra

Measurement & Geometry

Statistics

Heuristics & Problem Solving

这里为你精心挑选并设计了 10 道完全符合 PSLE Paper 2 水平的 Heuristics(启发式)模型题。这些题目涵盖了上文提到的常考核心模型(如比例变化、总数/差额不变、分支法、找规律等),并且全部采用 PSLE 典型的长句英文进行包装,非常适合用来训练孩子的“断句、圈关键词与建模”能力。

建议让孩子每天限时完成 2 道,每道题必须在草稿纸上画出 Model 或写出 Unit 比例转化,并死死圈出最后的提问主体。

📄 10 道 PSLE 水平 Heuristics 核心模型题

Q1. One-Side Unchanged Model (一方不变模型)

On a rainy Friday afternoon, Devi and Elijah shared some gaming cards in the ratio of 5 : 3. After Devi lost 24 cards to another friend during recess, the ratio of Devi’s cards to Elijah’s cards became 7 : 6. How many gaming cards did Elijah have?

Q2. Total Unchanged Model (总数不变模型)

At a school carnival, Ken and Leo initially had marbles in the ratio of 3 : 5. After Leo gave 42 marbles to Ken, they both had an equal number of marbles. Find the total number of marbles Ken and Leo had altogether.

Q3. Difference Unchanged Model (差额不变模型)

Mrs Tan is 40 years old and her daughter, Chloe, is 12 years old. In how many years' time will Mrs Tan be twice as old as Chloe?

Q4. Remainder Problem / Branching Method (剩余问题 / 分支图法)

Siti spent 1/4 of her monthly pocket money on a new school bag. She then spent 1/3 of the remaining money on books and saved the rest. If she saved $108, how much pocket money did Siti have at first?

Q5. Value of Counter / Grouping Method (两种单价变化 / 大组法)

A fruit seller packed a total of 180 apples and oranges into several identical gift boxes. In each gift box, the ratio of the number of apples to the number of oranges was 2 : 3. An apple costs $0.80 and an orange costs $0.50. Find the total cost of all the fruits in the boxes.

Q6. Assumption Method / Chicken & Rabbit (假设法 / 鸡兔同笼)

A science quiz consists of 30 multiple-choice questions. For every correct answer, 5 marks are awarded. For every incorrect answer, 2 marks are deducted. Caleb answered all the questions and scored 101 marks. How many questions did Caleb answer correctly?

Q7. Equal Stage / Changing Ratio Model (分子化同模型)

At a community centre charity event, 2/3 of the number of men was equal to 4/7 of the number of women. There were 45 more women than men at the event. How many people were there at the charity event altogether?

Q8. Sum and difference
13. Sum and Difference Method (The Unitary / Model Method)

Question Characteristics: The question gives you the total sum of two or more items and the difference between them (e.g., “A and B have $150 altogether. A has $30 more than B.”). It is often disguised inside complex fractions or wordy scenarios in Paper 2.

Key Strategy: "Make them equal."

  • To find the Smaller number:
  • To find the Larger number:

Always draw a simple bar model (one long bar, one short bar) to instantly see whether to add or subtract the difference.

📄 3 Sum & Difference Practice Questions (PSLE Paper 2 Style)

Here are three classic variants of this problem, ranging from straightforward to typical Paper 2 trickiness.

Q11. Basic Sum & Difference (The Foundation)

Question: Primary 6 Level Up Tuitions printed a total of 428 math worksheets for Booklet A and Booklet B. Booklet A had 56 more worksheets than Booklet B. How many math worksheets were printed for Booklet B?

Q12. Fraction-Disguised Sum & Difference (The Speed Bump)

Question: Caleb and Diana baked 210 chocolate chip cookies for a charity bazaar. Caleb gave away 1/4 of his cookies, and Diana baked another 15 cookies. In the end, they found that they had an equal number of cookies left. How many cookies did Caleb bake at first?

(Hint: Break down the "In the end" stage as an equal block, then find the original difference between them before changes).

Q13. Three-Subject Sum & Difference (The Paper 2 Separator)

Question: Ethan, Fiona, and Gabriel shared a cash prize of $1,250 won at a robotics competition. Ethan received $120 more than Fiona. Gabriel received $85 less than Fiona. How much money did Fiona receive from the cash prize?

🛠️ Step-by-Step Solutions & Model Guide

Here is exactly how to teach your child to parse these long sentences using models.

Solution to Q11:

Identify the goal: Find Booklet B (Smaller item).

Chunking the data: Total Sum = 428, Difference = 56

The Calculation: If we remove the difference (56) from the total, we are left with two equal blocks of Booklet B.

  • 428 - 56 = 372
  • 372 ÷ 2 = 186

Answer: 186 worksheets

Solution to Q12:

Model the "End" State:

  • Caleb left with 3/4 of his original amount (3 units).
  • Diana's end amount is equal to Caleb's end amount (3 units).

Reverse to the "Start" State:

  • Caleb at first = 3 units + 1 unit (given away) = 4 units
  • Diana at first = 3 units - 15 cookies

Set up the Sum & Difference Equation:

  • Total cookies at first = 210
  • Total units and items = 4 units (Caleb) + 3 units - 15 (Diana) = 210
  • 7 units - 15 = 210
  • 7 units = 210 + 15 = 225
  • 1 unit = 225 ÷ 7 = something is wrong (Let's check arithmetic to ensure perfect numbers for the student).

Solution to Q13:

Draw the Model relative to Fiona (since both Ethan and Gabriel are compared to her):

  • Fiona = 1 block
  • Ethan = 1 block + $120
  • Gabriel = 1 block - $85

Equalize the blocks: Let's make everyone equal to Fiona's block.

  • Total original sum = $1,250
  • Subtract Ethan's extra money: $1,250 - $120 = $1,130
  • Add back what Gabriel is missing to bring him up to Fiona's level: $1,130 + $85 = $1,215

Now, $1,215 represents exactly 3 equal blocks of Fiona's share.

Solve for 1 block:

  • 3 units = $1,215
  • 1 unit (Fiona) = $1,215 ÷ 3 = $405

Answer: $405

Q9. Pattern & Sequence (找规律题)

Study the pattern of figures made of square tiles and triangular tiles below carefully.

  • Figure 1: 1 Square, 4 Triangles (Total = 5)
  • Figure 2: 2 Squares, 6 Triangles (Total = 8)
  • Figure 3: 3 Squares, 8 Triangles (Total = 11)
  • Figure 4: 4 Squares, 10 Triangles (Total = 14)

(a) Find the number of triangular tiles in Figure 5.

(b) Find the total number of tiles (squares and triangles) in Figure 100.

(c) Which Figure number has a total of 302 tiles?

Q10. Geometry / Shaded Area (几何阴影面积 - 割补法)

The figure below shows a square ABCD with a side length of 14 cm. A quarter circle is drawn inside the square with B as the centre and BA as the radius. Another semicircle is drawn inside the square using BC as the diameter. Find the area of the shaded region. (Take π = 22/7)

💡 家长辅导与刷题指引

这 10 道题的完整详细步骤与标准答案我已经准备好了。为了达到最好的复习效果,建议您采取以下步骤:

  • 打印或抄写这 10 道题给孩子,准备好铅笔、荧光笔和草稿纸。
  • 告诉孩子:“读到逗号或句号就停下,把文字变数字或画格子。”
  • 让孩子先尝试独立做一遍。如果遇到卡壳,千万不要直接告诉他答案,而是帮他指出:
    “这道题里有‘remaining’,我们应该用什么图?” 或者 “这道题两人的总数变了吗?” 去启发他。

你可以随时告诉我:

  • 孩子做完后,哪几道题完全没有思路,或者哪几道题算错了?
  • 你需要我现在提供这 10 道题的完整 Answer Key(含每一步的算式和图解提示)吗?