Learning Objectives (National Curriculum - England)

• MA2/3.2 - Interpret and solve problems involving time, including converting between units of time
• Understand and use approximate equivalences between years, months, and weeks.
• Convert between different units of time, focusing on years, months, and weeks.

Success Criteria

By the end of this lesson, pupils will be able to:

• Accurately convert between years, months, and weeks using known equivalences (1 year = 12 months; 1 month ≈ 4 weeks; 1 year ≈ 52 weeks).
• Explain their reasoning behind their conversions clearly, justifying the steps they take.
• Apply conversions to solve real-life word problems involving time.
• Recognise and correct common errors in time conversion calculations.

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Lesson Duration

30 minutes
Class size: 30 pupils

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Resources

• Whiteboards and pens
• Interactive display or board
• Printed worksheet / exercise booklet with scaffolded questions
• Visual timeline of time units (years, months, weeks)
• Number lines marked in months and weeks for visual support

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Lesson Structure

1. Introduction (5 minutes)

Engagement and Contextual Hook:
"Imagine you want to know how many weeks are in your whole lifetime so far! Or you want to plan a birthday party and need to figure out how many months until your next birthday. Today, we will become 'time detectives' to convert between years, months, and weeks - which will help us with daily life problems."

Questioning to stimulate thinking:

• “How many months do you think are in a year? Why?”
• “Can anyone tell me if a year has exactly 52 weeks or something different? How do you know?”
• “If I tell you someone is 2 years old, can you estimate how many weeks that is? How are you working that out?”

Bloom’s taxonomy prompts:

• Remembering: What is the number of months in a year?
• Understanding: Can you explain why we say 1 month ≈ 4 weeks, not exact?
• Applying: How can you work out weeks in 3 years?
• Analysing: Why might using 4 weeks/month cause small errors when converting?
• Evaluating: Which method would be more accurate for converting months to weeks: 4 weeks/month or counting the actual days? Why?

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2. Teaching & Modelling (10 minutes)

Step 1: Display visual timeline on board

• Show one year = 12 months
• Show 1 month ≈ 4 weeks (explain approximation)
• Show 1 year ≈ 52 weeks

Step 2: Walk through example and model thinking aloud:

Example: Convert 3 years into months and weeks.

• Years to months: 3 years × 12 months = 36 months
• Years to weeks: 3 years × 52 weeks = 156 weeks

Write in pupils’ books:

Example:
3 years = ? months
3 years = ? weeks

3 years × 12 = 36 months
3 years × 52 = 156 weeks

Active reasoning questions as you model

• "Why do we multiply by 12 to get months?"
• "Why did we use 52 weeks instead of 48 (4×12) weeks for a year?"
• "What would happen if we used 48 weeks instead of 52? Would our answer be more or less accurate? Why?"

AfL:

• Use mini whiteboards here — ask pupils to show conversion of 2 years into months and weeks.
• Quickly scan and discuss any errors or misconceptions live.

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3. Guided Practice (8 minutes)

Task: Pupils convert given amounts of time from years to months, months to weeks, and weeks to months. Task increases in complexity.

Step	Task / Question	Scaffold
1	Convert 1 year into months and weeks.	Use times tables for 12 and 52.
2	How many weeks in 9 months? Explain your reasoning.	Use 4 weeks ≈ 1 month; reminder about approximation.
3	Sarah is 2 years and 6 months old. How many months old is she? And estimate weeks?	Break into parts: 2 years + 6 months. Use calculations.
4	Jamie says 5 years equals 240 weeks. Is this reasonable? Explain your thinking.	Compare 5×52 and 240 weeks. Identify error (approximation vs exact).

Targeted questioning to deepen reasoning:

• “Why did you choose to multiply/divide by this number?”
• “Explain how you separated the time into parts to convert.”
• “Do you think this method gives an exact or an approximate answer? How do you know?”
• “Jamie’s answer seems off. What steps would you take to check it?”

AfL:

• Circulate, listen in on explanations and reasoning.
• Use paired talk to compare methods and clarify misconceptions.

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4. Common Misconceptions & Addressing Difficulties (3 minutes)

• Believing there are exactly 4 weeks in every month (ignoring extra days). Clarify this causes approximations.
• Confusing months and weeks as fixed values that convert exactly.
• Adding weeks and months directly without converting units first.
• Forgetting to multiply both parts when converting combined units (e.g., 2 years and 6 months → each converted separately).

Opportunity for class discussion:

• “Why might using 4 weeks for every month lead to small errors in longer time calculations?”
• "How might you improve accuracy if needed?"

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5. Plenary (4 minutes)

Oral quiz with reasoning: Call out time conversions and have pupils explain answer aloud or write a sentence for each question. Encourage justification:

e.g.,

• How many months in 4 years? Tell me how you worked it out.
• Estimate how many weeks in 10 months; explain your method.
• Someone says 1 year has 48 weeks. How would you respond?
• Convert 1 year and 3 months to weeks; explain each step.

Summarise learning:
“We’ve practised converting between years, months, and weeks and learned why some conversions are approximate. Converting time helps us understand durations better and solve real-world problems.”

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Alignment to White Rose Maths Scheme

This lesson aligns with White Rose Year 4 Block 3 (Number – Multiplication & Division) and Year 3 & 4 Measurement (Time), supporting pupils to develop fluency and reasoning with time conversions and solving multi-step problems involving measures.

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Additional Notes for Teachers

• Encourage reminding pupils that months vary in length but for ease, we use approximations in calculations.
• Use visual timelines or number lines to support conceptual understanding.
• Promote active verbal reasoning regularly to deepen mathematical thinking.
• Use the plenary to consolidate understanding and reveal any misconceptions for next lesson focus.

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Summary of AfL Points

Stage	AfL Strategy	Purpose
Modelling	Mini whiteboards quick check	Check immediate understanding of multiplication for months/weeks
Guided practice	Paired talk, teacher observations	Identify reasoning and errors, scaffold support
Plenary	Oral reasoning and explanation	Consolidate learning and explore misconceptions

This detailed and targeted lesson plan will build confident, reasoning mathematicians capable of applying their knowledge in and out of the classroom!