Free Grade 3 Introducing Imaginary Unit Common Errors Lessons
Free Grade 3 lessons for Introducing Imaginary Unit Common Errors: 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
Stretch
20 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- UnderstandExplain introducing imaginary unit common errors
Explain introducing imaginary unit common errors accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate introducing imaginary unit common errors
Calculate introducing imaginary unit common errors accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare introducing imaginary unit common errors
Compare introducing imaginary unit common errors accurately in a familiar context.
Assessed by: Exit ticket of four short items
- EvaluateJustify introducing imaginary unit common errors
Justify introducing imaginary unit common errors 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 Introducing Imaginary Unit Common Errors 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 7 km to m.[1]
- 2.Convert 3 cm to mm.[1]
- 3.Convert 2 kg to g.[1]
- 4.Convert 5 kg to g.[1]
- 5.Convert 2.2 kg to g.[2]
- 6.Convert 5.2 cm to mm.[2]
- 7.Convert 1.2 km to m.[2]
- 8.Convert 5.4 L to mL.[2]
- 9.Convert 6.4 m to cm.[3]
- 10.Convert 2.3 cm to mm.[3]
- 11.Convert 7.3 km to m.[3]
- 12.Convert 7.6 cm to mm.[3]
Show answers and working
1. 7000 m
1 km = 1000 m. 7 × 1000 = 7000 m.
2. 30 mm
1 cm = 10 mm. 3 × 10 = 30 mm.
3. 2000 g
1 kg = 1000 g. 2 × 1000 = 2000 g.
4. 5000 g
1 kg = 1000 g. 5 × 1000 = 5000 g.
5. 2200 g
1 kg = 1000 g. 2.2 × 1000 = 2200 g.
6. 52 mm
1 cm = 10 mm. 5.2 × 10 = 52 mm.
7. 1200 m
1 km = 1000 m. 1.2 × 1000 = 1200 m.
8. 5400 mL
1 L = 1000 mL. 5.4 × 1000 = 5400 mL.
9. 640 cm
1 m = 100 cm. 6.4 × 100 = 640 cm.
10. 23 mm
1 cm = 10 mm. 2.3 × 10 = 23 mm.
11. 7300 m
1 km = 1000 m. 7.3 × 1000 = 7300 m.
12. 76 mm
1 cm = 10 mm. 7.6 × 10 = 76 mm.
Worked examples
Convert 7 cm to mm.
- 1 cm = 10 mm.
- 7 × 10 = 70 mm.
- Answer: 70 mm
Convert 8.1 km to m.
- 1 km = 1000 m.
- 8.1 × 1000 = 8100 m.
- Answer: 8100 m
Convert 5.7 cm to mm.
- 1 cm = 10 mm.
- 5.7 × 10 = 57 mm.
- Answer: 57 mm
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.
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Frequently asked
- Is this Grade 3 Introducing Imaginary Unit Common Errors lesson really free?
- Yes. Every lessons 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 Imaginary Unit Word Problems, Introducing Imaginary Unit Techniques, Real Numbers. Each one has its own free lesson, worksheet and quiz.
- How is the lesson 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 Introducing Imaginary Unit Common Errors?
- Move on to Working with Imaginary Unit, Imaginary Unit in Context, which build directly on this idea.
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