Write the three fixture times on the IWB and invite hands. Expect mixed answers for 17:45, some pupils will guess 5:45 pm correctly, others will be stuck on 'why is it not just 5:45 then?'. Hold the question open; the rule lands in the next step. If a pupil says 'you take 12 away', revoice, 'yes, that's the rule we're about to write down', and bank the language for later.

Point at each clock in turn and say the time both ways aloud: 'thirteen hundred, which is one o'clock in the afternoon'; 'eighteen thirty, which is half past six in the evening'; 'twenty-one fifteen, which is quarter past nine at night'. After the third clock, pause and write the rule on the side of the IWB: after midday, take 12 off the hours to get the pm time. Work out with the class 13 − 12 = 1, 18 − 12 = 6, 21 − 12 = 9.

This round is for talking it through together, pupils take turns at the board and the class agrees or corrects out loud.

Walk each example in the new order. 2:45 pm → 14:45: ask the pupil 'is it morning or afternoon?' then 'so do we keep the 2 or add 12?'. 11:20 am → 11:20: this is the trap, deliberately placed second so pupils don't pattern-lock on +12. If a pupil says 'is it 23:20?', revoice the rule, 'morning times don't need the rule because they're already under 12'. 4:00 pm → 16:00: work out 4 + 12 = 16, and say it aloud as 'sixteen hundred'. 7:30 pm → 19:30: work out 7 + 12 = 19. Rotate four pupils to the board across the four examples.

This round is the practice bank. Start by working the first problem aloud with the class to model the count-up strategy, then pupils take turns at the board for the next three. The class confirms each answer before moving on. The same 4-problem bank reruns at home as tonight's homework, so keep the board work brisk rather than over-explaining.

For the worked example, narrate the count-up at each landing: '07:30 plus 30 minutes brings us to 08:00, then 1 hour brings us to 09:00, then 15 minutes more brings us to 09:15'. Check each landing point with the class as you go. For each subsequent challenge the clock opens on the start time and the elapsed readout counts up live as the pupil drags. Look for the cross-noon case (09:00 + 4 h 15 m = 13:15), pupils may set 13:15 by counting the hours hand round, but if anyone says '13:15 is one fifteen in the afternoon' revoice the rule for the class. Remind pupils watching from their seats to work out the answer in their heads before the pupil at the board lands the hands.