🎓 Fast Subtraction Tricks – Year 3 (ACARA Code : AC9M3N03)
🎯Focus:
🧩 Learn part-part-whole models to split numbers
🔄 Apply the inverse relationship between addition and subtraction
🧠 Build mental math and problem-solving skills
📚 Aligned with Year 3 Australian Curriculum – Number and Algebra
Key Ideas (Quick Guide)
- 🧩 Part-Part-Whole Models : Break a number into parts to see addition/subtraction.
- Example: 12 = 7 + 5
- 🔄 Inverse Operations : Addition & subtraction undo each other.
- Example: 12 – 7 = 5; 12 – 5 = 7
- 🧠 Mental Math Practice : Helps find missing numbers quickly.
🎥Video Lessons
💡 Video Tips:
✏️ Pause videos to draw diagrams
🟦🟨🟥 Use colored counters or blocks
🗣️ Say numbers out loud for mental math practice
🔄 Check answers using the inverse operation method
🧩 Mini Quiz – Quick Check
Try these after watching the video:
❓Question 1: 12 split into 7 + ? → ? = ?
✅ Answer: 5
❓Question 2: 15 – ? = 8, what is the missing number?
✅ Answer: 7
❓Question 3: True or False: 12 – 7 = 5 and 12 – 5 = 7 ✅/❌
✅ Answer: True
❓Question 4: Which method helps find missing numbers? a) Inverse b) Multiplication c) Division
✅ Answer: Inverse
❓Question 5: 7 + 5 = ?
✅ Answer: 12
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📚 Other Lessons in This Unit
🔢 Visual Place Value Models to Solve Big Numbers Easily
🏗️ Fast Math Tricks for Subtraction: Mental Math Shortcuts Explained
🧠 Flexible Math Strategies: Standard vs Non‑Standard Partitions Explained