Give five seconds of quiet think-time, then take three hands-up answers. Listen for the common slip of writing 2.5 and 'shifting the point' to 25. Don't correct it yet — hold it as the puzzle the lesson unpicks.

Point at each clock in turn. Say the fact each one shows, then pin the big idea: it takes lots of small units to fill one big unit, and none of these jumps are tens, so we can't slide a decimal point — we multiply or divide.

• Second hand — the whole way round is one notch of the minute hand: 60 seconds = 1 minute.
• Minute hand — the whole way round is one hour: 60 minutes = 1 hour.
• Whole day, twenty-four hours make one day: this is where the 24 comes from; a day is not 10 or 100 hours.

Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud.

Build 2½ hours by hand first, on the board, before touching the machine: 2 × 60 = 120, then ½ × 60 = 30, then 120 + 30 = 150. Hold out for 150 and head off the '25' answer — say we multiplied, we didn't slide the point. Then take a prediction before running the machine: set the rule to × 60 and run 3 → 180. Swap the rule to ÷ 60 and run 180 → 3 so the class sees minutes-to-hours is the reverse. If time allows, swap the rule to × 24 and send 2 days through to meet days-to-hours while the multiply idea is fresh.

This is the practice round — pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

For each challenge, ask the class first: multiply or divide — and by what? The film stretch is a double step: × 60 for hours-to-minutes (120), then × 60 again for minutes-to-seconds (7,200). Let a strong pupil talk the class through the second multiply.