🎓 Year 3 (ACARA Code : AC9M3A01)
🎯Focus:
🧩 Apply inverse operations to real-life “start-change-result” problems
📊 Create bar model diagrams
⚡ Build confidence solving word problems with missing starting amounts
Video Lessons
📹 Video Lesson Tips
- Pause after each money/marble example and ask students to identify “Start = Spent + Left Over”
- Have students draw a quick bar model during pauses (total bar = spent part + remaining part)
- Ask students to say the inverse operation out loud (“subtraction? → add back!”)
- Replay real-world scenarios and have students create their own similar problems
- Use the “work backwards” phrase repeatedly to build the habit
💡 Key Ideas (Quick Guide)
🧩 Start-Change-Result Pattern – Every word problem follows: START (often missing) → CHANGE (spent/taken) → RESULT (left/remain)
🧩 Inverse Thinking – Work BACKWARDS: Result + Change = Start ($14 left + $28 spent = $42 start)
🧩 Bar Model Magic – Draw a total bar, mark the known parts, find the missing start
🧩 Real-Life Power – Money spent, marbles taken, discounts saved – same pattern every time!
🧩 Mini Quiz – Quick Check
Try these after watching the video:
❓Question 1:Peter spent $28 and has $14 left. How much did he start with?
✅ Answer: $42
❓Question 2: 35 marbles taken out, 15 remain. Original amount?
✅ Answer: 50 marbles
❓Question 3: What strategy do you use for “spent + left = start”?
✅ Answer: Add them together (inverse operation)
❓Question 4: A shirt had $12 discount. Paid $38. Original price?
✅ Answer: $50
❓Question 5: Draw a quick bar model: $39 spent, $61 left. (What equals total?)
✅ Answer: $39 + $61 = $100 start
Scored:
5/5 💯 = Champion!
3–4/5 🌟 = Great Work!
0–2/5 🔄 = Watch the video again!
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📚 Other Lessons in This Unit
🚀 Learning Path (Recommended Order)
| Step | 🔗 Lesson | 💡 What You Learn |
|---|---|---|
| 1 | 🧠 Addition and Subtraction Word Problems with Missing Numbers for Year 3 ⭐ You are here⭐ | Apply inverse operations to real-life “start-change-result” problems |
| 2 | 🔢Partitioning Numbers, Part-Part-Whole and Bar Models | Practise partitioning numbers and learn reading bar models |
| 3 | ✏️Inverse Operations in Year 3: Finding Unknown Numbers | Use fact families to find unknown numbers in equations and check answers by working backwards. |
| 4 | 🧩 Inverse Operations: Connecting Addition and Subtraction | Deepen their understanding of inverse operations by connecting mental addition and subtraction |