Time Detective

Overview

Students are introduced to reading and writing time using am, pm and 24-hour time, and then apply this in a fun “Time Detective” scavenger hunt. The lesson builds the foundation needed to later calculate durations between times.

Learning intentions

• Students will be able to read times written as am/pm and 24-hour time.
• Students will be able to convert between am/pm time and 24-hour time for common classroom examples.
• Students will explain how they know which part of the day a time belongs to.
• Students will record answers clearly using digital-style time writing (e.g. 07:15, 19:30, 1:30 pm).

Success criteria

• I can identify whether a time is am, pm, or 24-hour time.
• I can write a time in both am/pm and 24-hour formats for given examples.
• I can justify my conversion using number clues (12-hour turning points and “past the half-day”).
• I can find and match the correct time cards accurately in the scavenger hunt.

Curriculum links

• Measurement — solve problems involving duration of time including situations involving am and pm and conversions between units of time.
• Measurement — interpret scaled and digital instruments when measuring and comparing duration, including reading time to determine duration.
• Number — develop efficient strategies using appropriate digital tools to solve problems involving addition/subtraction where needed for time-related tasks (later connections).
• Number — use mathematical modelling to solve practical problems and communicate solutions in terms of the situation (time timetables).

Lesson structure (45 minutes)

1. 0–5 min · Hook (Time Detective set-up). Teacher shows 3 time displays on the board: “7:00 am”, “1:00 pm”, “19:00” and asks: “Which ones are morning, afternoon, and 24-hour time? How do you know?” Students answer on mini-whiteboards.

2. 5–15 min · Direct teach (am/pm vs 24-hour basics). Teacher explains a simple rule set with examples and adds a “Turnaround” chart:

• For am times (except 12:xx am), keep the hour number the same (e.g. 3:15 am → 03:15).
• For pm times, add 12 to the hour except when it’s 12:xx pm (e.g. 1:20 pm → 13:20; 12:40 pm → 12:40).
• For 24-hour to am/pm: 00:xx–11:xx is am (01:10 → 1:10 am), 12:xx is pm for 12:00–12:59 (12:30 → 12:30 pm), 13:xx–23:xx is pm (19:05 → 7:05 pm). Students practise 4 quick conversions independently (teacher writes answers on board for checking):
• 7:30 am →? (24-hour)
• 1:15 pm →? (24-hour)
• 19:00 →? (am/pm)
• 12:05 pm →? (24-hour)

3. 15–20 min · Guided game warm-up (Human clock). Teacher labels the room corners: “am”, “pm”, and “24-hour”. Calls out one time at a time (e.g. “9:00 am”, “15:30”, “5:45 pm”). Students move to the matching corner and state one conversion they could make (e.g. 15:30 → 3:30 pm).

4. 20–35 min · Interactive game (Time Detective scavenger hunt). Teacher groups students (pairs or trios) and explains the mission: “Find 8 cards around the room. Each card has one time written in a particular format. You must match it with its equivalent time in the other format and record both.” Students rotate through stations holding a worksheet grid with columns: Found time card, Converted time (other format), Reason clue (e.g. “pm means add 12”). Card set examples to include:

• 7:10 am ↔ 07:10
• 12:05 pm ↔ 12:05
• 1:25 pm ↔ 13:25
• 6:40 pm ↔ 18:40
• 00:15 ↔ 12:15 am
• 11:50 am ↔ 11:50
• 19:30 ↔ 7:30 pm
• 23:05 ↔ 11:05 pm Teacher circulates, checking conversions and prompting with sentence starters: “Because it’s pm, I add 12…” or “Because it’s 19:30, it’s after 12 so it’s pm…”

5. 35–42 min · Share & debrief (whole class checks). Teacher selects 4 student answers (from different groups) and asks: “Is the conversion correct? What rule did you use?” Students justify verbally and teacher refines misconceptions (especially around 12:00 and converting 12:xx pm vs 12:xx am).

6. 42–45 min · Exit ticket (quick assessment). Students complete 3 items independently on paper:

• Convert: 3:20 pm → 24-hour time.
• Convert: 09:15 → am/pm time.
• Identify: 12:30 pm is am or pm? (circle)

Resources

• Time Detective card set (8–12 cards) including am/pm and 24-hour times
• Student scavenger hunt worksheet (conversion grid with reason clue line)
• Mini-whiteboards and markers
• Room corner signs: “am”, “pm”, “24-hour”
• “Turnaround” anchor chart (12:xx rules and add 12 strategy)
• Timer for group rotations
• Exit ticket slips

Assessment

• Formative during guided conversions (check mini-whiteboards for misconceptions about am/pm and 24-hour turning points).
• Game observation: teacher records which students match correct equivalences and whether they use an explanation clue.
• Exit ticket marking: accuracy and correct use of the key rule for 12:xx times.

Differentiation

• Support for below-average learners:
• Provide a “rule strip” on the worksheet (add 12 for pm except 12:xx pm; 00:xx is 12:xx am).
• Sentence starters for reasons: “It’s pm so I…” “24-hour time 19:00 is…”
• Offer a partially completed worksheet for one station match (first example fully modelled).
• Extension for above-average learners:
• Include one or two challenge cards with times close to boundaries (e.g. 11:59 am, 12:01 pm, 23:59) and ask students to explain the boundary rule.
• Ask students to create one extra matching pair (am/pm and 24-hour) and write a rule for their conversion.
• EAL considerations:
• Use visual supports (am/pm meaning via morning/afternoon icons; 24-hour chart).
• Encourage partner talk using the sentence starters.
• SEN/attention support:
• Limit scavenger hunt cards per round (e.g. 4 found first, check, then next 4).
• Assign clear roles within pairs (reader, writer, checker).

Extension (optional)

• If time remains or for a fast finish: students write a mini timetable for school activities using at least two formats (am/pm and 24-hour) and underline the key conversion they used.