NCERT Maths Mela, Class 5, textbook pages 155–163

How to teach Class 5 Maths Chapter 12, Racing Seconds, at home

Seconds, elapsed time and 24-hour time, taught with things you already have at home: a 10-minute activity, a game for the week, a 5-day plan and the mistakes to watch for.

01:56minutes : seconds

NCERT Class 5 Maths Chapter 12 Racing Seconds: what it teaches

Stopwatches bring seconds into time. Your child finds elapsed time, converts minutes and seconds, compares durations, and reads and writes times in 12-hour and 24-hour formats.

Why it matters later. Elapsed time and the 24-hour clock are used in timetables, travel and science.

See it: this chapter in pictures

1234567891011129:15 a.m.12345678910111211:30 a.m.2 h 15 min
Count whole hours, then minutes.
12-hour24-hour5:30 a.m.05:3012 noon12:005:45 p.m.17:45
After noon, add 12 to the hour.
1 min 25 s= 60 s + 25 s= 85 seconds
1 minute = 60 seconds.

You need

  • a phone stopwatch
  • a clock
  • a train or bus timetable (online)

Tonight’s 10 minutes

  1. Time 10 jumps, a 20-metre walk and writing your name. Which took most seconds?
  2. Find elapsed time: 9:15 a.m. to 11:30 a.m.
  3. Convert 1 minute 25 seconds into seconds.
  4. Read a train timetable and change 17:45 to 12-hour time.

Words to use

  • second
  • minute
  • hour
  • elapsed time
  • a.m.
  • p.m.
  • 24-hour time

Watch for

  • Treating minutes like hundreds (1:50 + 20 min = 1:70). 60 minutes make an hour: 1:50 + 20 min = 2:10.
  • Confusing 12 noon and 12 midnight in 24-hour time. Noon is 12:00; midnight is 00:00.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouYoga from 9:15 to 11:30. How long?

Your child9:15 to 11:15 is 2 hours, plus 15 minutes.

You17:45 on a train ticket?

Your child5:45 p.m.

YouHow many seconds in 1 minute 25?

Your child85.

A game for this week: Timetable detective

  1. Find a real train timetable online.
  2. Ask: how long is the journey?
  3. Convert departure times to 12-hour format.
  4. Correct answers score points.

A 5-day plan, 10 minutes a day

  1. Day 1Time activities in seconds.
  2. Day 2Elapsed time on a clock.
  3. Day 3Minutes to seconds.
  4. Day 424-hour time from timetables.
  5. Day 5Timetable detective.

Everyday moments to practise

  • Train and flight timetables.
  • Race timings in seconds.
  • Cooking times.
  • Screen-time limits.

Quick check

Ask these at the end of the week. Tap to see the answer.

9:15 a.m. to 11:30 a.m.?

2 hours 15 minutes.

1 minute 25 seconds in seconds?

85.

17:45 in 12-hour time?

5:45 p.m.

Ready for the next chapter when your child…

  • Finds elapsed time in hours and minutes.
  • Converts minutes and seconds.
  • Reads 24-hour time.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Maths Mela (Class 5). See the full Class 5 parent guide for every chapter.

Questions parents ask

How many seconds in a minute?

60.

How do I convert 24-hour time?

Subtract 12 from hours above 12 and add p.m.: 17:45 is 5:45 p.m.

How do I find elapsed time?

Count on in hours, then minutes, from start to end.