Free Grade 3 Imaginary Unit Lesson Plans
Free Grade 3 lesson plans for Imaginary Unit: 12 real questions with a full answer key and worked solutions. Metric units change by powers of 10: 10 mm in a cm, 100 cm in a m, 1000 m in a km. Multiply to convert to a smaller unit, divide to convert to a bigger one.
Free
Core
35 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain imaginary unit
Explain imaginary unit accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate imaginary unit
Calculate imaginary unit accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare imaginary unit
Compare imaginary unit accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify imaginary unit
Justify imaginary unit 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 Imaginary Unit works
Metric units change by powers of 10: 10 mm in a cm, 100 cm in a m, 1000 m in a km. Multiply to convert to a smaller unit, divide to convert to a bigger one.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.Convert 9 L to mL.[1]
- 2.Convert 4 cm to mm.[1]
- 3.Convert 4 km to m.[1]
- 4.Convert 4 kg to g.[1]
- 5.Convert 1.1 kg to g.[2]
- 6.Convert 2.2 kg to g.[2]
- 7.Convert 6.5 km to m.[2]
- 8.Convert 9.4 kg to g.[2]
- 9.Convert 5.6 m to cm.[3]
- 10.Convert 4.3 kg to g.[3]
- 11.Convert 3.6 L to mL.[3]
- 12.Convert 5 m to cm.[3]
Show answers and working
1. 9000 mL
1 L = 1000 mL. 9 × 1000 = 9000 mL.
2. 40 mm
1 cm = 10 mm. 4 × 10 = 40 mm.
3. 4000 m
1 km = 1000 m. 4 × 1000 = 4000 m.
4. 4000 g
1 kg = 1000 g. 4 × 1000 = 4000 g.
5. 1100 g
1 kg = 1000 g. 1.1 × 1000 = 1100 g.
6. 2200 g
1 kg = 1000 g. 2.2 × 1000 = 2200 g.
7. 6500 m
1 km = 1000 m. 6.5 × 1000 = 6500 m.
8. 9400 g
1 kg = 1000 g. 9.4 × 1000 = 9400 g.
9. 560 cm
1 m = 100 cm. 5.6 × 100 = 560 cm.
10. 4300 g
1 kg = 1000 g. 4.3 × 1000 = 4300 g.
11. 3600 mL
1 L = 1000 mL. 3.6 × 1000 = 3600 mL.
12. 500 cm
1 m = 100 cm. 5 × 100 = 500 cm.
Worked examples
Convert 6 L to mL.
- 1 L = 1000 mL.
- 6 × 1000 = 6000 mL.
- Answer: 6000 mL
Convert 7 km to m.
- 1 km = 1000 m.
- 7 × 1000 = 7000 m.
- Answer: 7000 m
Convert 8.5 kg to g.
- 1 kg = 1000 g.
- 8.5 × 1000 = 8500 g.
- Answer: 8500 g
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Divides when converting to a smaller unit.
Correction: Smaller units mean more of them — multiply.
Uses 100 for every conversion.
Correction: Learn which pairs use 10, 100 or 1000.
Teacher tips
- · Keep a conversion staircase on the wall.
Parent tips
- · Weigh fruit at the shop and convert kg to g.
Real-life applications
- · Cooking, measuring height, reading road signs.
Assessment objectives
How mastery is evidenced, and which standards it maps to.
Every free resource for Imaginary Unit
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Learn — Meet the idea.
Practice — Build fluency.
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Frequently asked
- Is this Grade 3 Imaginary Unit 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 Real Numbers. 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 Imaginary Unit?
- Move on to Argand Diagram, Complex Arithmetic, Modulus and Argument, Whole Numbers, which build directly on this idea.
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