Free Grade 3 Working with Simple Interest Lesson Plans
Free Grade 3 lesson plans for Working with Simple Interest: 12 real questions with a full answer key and worked solutions. Per cent means 'out of 100'. Find 10% by dividing by 10 or 1% by dividing by 100, then build up. For an increase or decrease, use a multiplier.
Free
Core
15 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain working with simple interest
Explain working with simple interest accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate working with simple interest
Calculate working with simple interest accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare working with simple interest
Compare working with simple interest accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify working with simple interest
Justify working with simple interest accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Working with Simple Interest works
Per cent means 'out of 100'. Find 10% by dividing by 10 or 1% by dividing by 100, then build up. For an increase or decrease, use a multiplier.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Find 50% of 160.[1]
- 2.Find 10% of 40.[1]
- 3.Find 25% of 800.[1]
- 4.Find 75% of 480.[1]
- 5.Find 60% of 520.[2]
- 6.Find 40% of 700.[2]
- 7.Find 30% of 160.[2]
- 8.Find 60% of 500.[2]
- 9.Decrease $40.00 by 30%.[3]
- 10.Increase $640.00 by 20%.[3]
- 11.Increase $580.00 by 60%.[3]
- 12.Decrease $340.00 by 60%.[3]
Show answers and working
1. 80
1% of 160 = 1.6. 50% = 1.6 × 50 = 80.
2. 4
1% of 40 = 0.4. 10% = 0.4 × 10 = 4.
3. 200
1% of 800 = 8. 25% = 8 × 25 = 200.
4. 360
1% of 480 = 4.8. 75% = 4.8 × 75 = 360.
5. 312
1% of 520 = 5.2. 60% = 5.2 × 60 = 312.
6. 280
1% of 700 = 7. 40% = 7 × 40 = 280.
7. 48
1% of 160 = 1.6. 30% = 1.6 × 30 = 48.
8. 300
1% of 500 = 5. 60% = 5 × 60 = 300.
9. $28.00
Multiplier: 1 − 0.3 = 0.7. 40 × 0.7 = 28.
10. $768.00
Multiplier: 1 + 0.2 = 1.2. 640 × 1.2 = 768.
11. $928.00
Multiplier: 1 + 0.6 = 1.6. 580 × 1.6 = 928.
12. $136.00
Multiplier: 1 − 0.6 = 0.4. 340 × 0.4 = 136.
Worked examples
Find 50% of 320.
- 1% of 320 = 3.2.
- 50% = 3.2 × 50 = 160.
- Answer: 160
Find 12.5% of 140.
- 1% of 140 = 1.4.
- 12.5% = 1.4 × 12.5 = 17.5.
- Answer: 17.5
Increase $660.00 by 30%.
- Multiplier: 1 + 0.3 = 1.3.
- 660 × 1.3 = 858.
- Answer: $858.00
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Finds 10% and stops when asked for a 10% decrease.
Correction: Subtract the 10% from the original.
Thinks a 50% rise then 50% fall returns to the start.
Correction: The second percentage is of a different amount.
Teacher tips
- · Teach 10%, 5%, 1% building blocks before multipliers.
Parent tips
- · Work out the tip at a restaurant together.
Real-life applications
- · Sales, tips, tax and interest.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
Every free resource for Working with Simple Interest
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Frequently asked
- Is this Grade 3 Working with Simple Interest lesson plan really free?
- Yes. Every lesson plans on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Introducing Simple Interest, Percentage Change. Each one has its own free lesson, worksheet and quiz.
- How is the lesson plan sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Working with Simple Interest?
- Move on to Simple Interest in Context, Percentage of an Amount, Percentage Increase, Percentage Decrease, which build directly on this idea.
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