Math // Measurement

Telling time to the minute (age 9+)

Solve problems involving converting between units of time (hours↔minutes, minutes↔seconds, years↔months, weeks↔days)

Ages
9 to 10
Type
Method
Builds on
2 topics
Leads to
2 topics
Standards
1 code

Quick check

If the learner needs to convert 2 hours 35 minutes into just minutes, can they do it — and then convert 180 seconds into minutes and seconds?

Ask this to see whether the topic is secure.

Topic // Mastery

What mastery looks like

What a learner can do once this topic is secure.
  • Convert 3 hours 25 minutes to 205 minutes
  • A programme lasts 150 seconds — express in minutes and seconds
  • How many days are in 8 weeks and 3 days?

Topic // Map

Where this fits

What to learn first and what this topic opens up, with the reason for each link. Required links come first.
  • RequiredMust come first
  • HelpfulHelps, but not essential

Before this

2 topics

You are here

Telling time to the minute (age 9+)

Ages 9 to 10 // Method

Leads to

2 topics
  • Reading tablesHelpful

    Data & Statistics // Ages 9 to 10

    Time conversion supports interpreting timetables

  • Egyptian Timelines and MapsHelpful

    History // Ancient Egypt // Ages 9 to 10

    Reading and constructing historical timelines requires understanding time unit conversions (decades, centuries, millennia)

Topic // Research-informed

Teaching notes

From the Marble Skill Taxonomy. These notes have not been validated in classrooms, so treat them as a starting point for your own judgement.

The approach

Children convert between units of time — hours↔minutes, minutes↔seconds, years↔months, weeks↔days — including mixed quantities (e.g. 3 hours 25 minutes = 3×60 + 25 = 205 minutes). The core idea is MULTIPLICATIVE conversion (×60, ×7, ×12) using known number facts, and resisting the base-10 pull that wrongly assumes 100 seconds in a minute or 100 minutes in an hour. Reverse conversions require dividing and expressing the remainder (150 s → 2 min 30 s). Documented errors are additive rather than multiplicative reasoning, base-10 assumptions, mishandling the remainder/second unit in mixed quantities, and treating every month as exactly 4 weeks.

Common misconceptions

  • Uses additive reasoning instead of multiplicative for conversions
  • Assumes base-10 (100 seconds in a minute, 100 minutes in an hour)
  • Thinks every month is exactly 4 weeks / all months are the same length
  • Converts a mixed quantity by ignoring the remainder or the second unit

Useful representations

  • Conversion tables (Days-Weeks, Years-Months, Minutes-Seconds)
  • The x60 / x7 / x12 rate as a known-fact chain (36 ÷ 6 = 6, so 360 s = 6 min)
  • A number track for counting leap years / weeks
  • A bar model splitting a mixed quantity into whole units + remainder

Teaching practices

  • Use multiplicative reasoning with known facts (x60, x7, x12), not repeated addition
  • Convert mixed quantities in two parts: whole units x rate, then add the remainder (3x60 + 25)
  • Confront the base-10 pull explicitly: 60 seconds in a minute, not 100
  • Handle the reverse (150 s -> 2 min 30 s) by dividing and expressing the remainder
  • Flag irregular units — months vary; about 4 weeks in a month is approximate, not exact

Activities to try

  1. 1

    Multiply-then-combine with a conversion machine

    Why it works: Converting units of time is multiply (by the fixed rate) then combine the remainder — not counting up — and for seconds, minutes and hours the grouping is 60, not 100.

    1. Take a mixed quantity such as 3 hours 25 minutes and convert it: multiply the whole units by the rate (3 × 60 = 180 minutes), then add the remaining 25 to get 205 minutes.
    2. State out loud whether you counted up or multiplied, and why multiplying is faster.
    3. Work a reverse conversion: take 150 seconds, group it into sixties — two full groups of 60 make 2 minutes, with 30 seconds left over, giving '2 minutes 30 seconds'.
    4. Test the tempting '100 to a minute' idea against grouping real seconds into sixties, and describe what goes wrong.
  2. 2

    Known-facts conversion with a base-10 trap item

    Why it works: Secure conversions rest on known multiplication facts and on keeping the remainder; the common wrong answers to the 150-seconds item — '1.5 minutes' and '2 minutes' — correspond to base-10 thinking and to dropping the remainder.

    1. Fill in conversions such as '3 h 25 min = ___ min' and show the multiply-then-add working.
    2. Match a seconds amount (e.g. 150 s) to its minutes-and-seconds form.
    3. Choose the correct reading of 150 seconds and explain why '1.5 minutes' (base-10 thinking) and '2 minutes' (dropped remainder) are both wrong.
    4. Convert 8 weeks 3 days to days using 8 × 7 = 56, then + 3 = 59 days.
  3. 3

    Irregular units: months, weeks and the calendar

    Why it works: Some time units convert by exact fixed rates (7 days per week, 60 seconds per minute, 12 months per year) while month LENGTHS are irregular, so 'a month ≈ 4 weeks' cannot be used as an exact conversion to days.

    1. Use a real calendar to count the days in several different months, including February, and record what you find: months have 28, 29 (February in a leap year), 30 or 31 days.
    2. State why 'about 4 weeks in a month' is an approximation, not an exact conversion.
    3. Contrast the exact fact (1 week = 7 days) with the approximate month fact, and explain how you would convert months to days versus weeks to days.

Topic // Standards

Curriculum standards

Codes for the curriculum statements this topic maps to. Each publisher owns its standard text.
The national curriculum in England: Key stages 1 and 2 framework document
Ma5/3.1f

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