Time — Class 3 Mathematics (Samacheer Kalvi)
TN State Board (Samacheer Kalvi) Class 3 Mathematics. Clocks to five minutes, AM and PM, and the calendar.
1. The two hands do different jobs
The short hand gives the hour. The long hand gives the minutes.
On the minute hand, each number on the clock face is worth five minutes, not one. The long hand at 1 means 5 minutes past, at 2 means 10 past, at 3 means 15 past.
| Long hand at | Minutes past |
|---|---|
| 12 | 0 |
| 3 | 15 |
| 6 | 30 |
| 9 | 45 |
2. Quarter past, half past, quarter to
An hour has 60 minutes, so a quarter of an hour is 15 minutes.
- Quarter past 4 is 4:15
- Half past 4 is 4:30
- Quarter to 5 is 4:45
Notice the last one. At 4:45 we say quarter to five, not quarter to four, because the next hour is the one being approached.
Once the minute hand passes 30, it is usually clearer to count towards the next hour. So 9:35 is 25 minutes to 10, and 9:50 is 10 minutes to 10.
This is worth care. Reading 9:50 as "fifty minutes past nine" makes it sound like the morning has barely moved past nine, when in truth ten o'clock is almost here.
3. AM and PM
The clock face only shows twelve hours, but a day has twenty-four. AM and PM say which half of the day is meant.
- AM runs from midnight to noon: early morning, breakfast, school assembly.
- PM runs from noon to midnight: lunch, evening play, bedtime.
So 7 AM is before school and 7 PM is after dinner, and the clock face looks identical for both.
4. The calendar
A year has 12 months, and they do not all have the same length.
| Days | Months |
|---|---|
| 31 | January, March, May, July, August, October, December |
| 30 | April, June, September, November |
| 28 or 29 | February |
The knuckle trick helps. Make a fist and go along the knuckles and gaps: a knuckle means 31 days, a gap means 30. February is the one exception.
February has 28 days in an ordinary year and 29 in a leap year, which comes once every four years. A leap year has 366 days in total.
5. Working out durations
To find the number of days between two dates in the same month, subtract.
From April 10 to April 25 is 25 − 10 = 15 days.
To find the day of the week for a later date, remember that the same weekday returns every 7 days. If March 1 is a Monday, then March 8 and March 15 are also Mondays.
6. Worked examples
Example 1. Write 4:15 and 11:45 in words.
4:15 is quarter past four. 11:45 is quarter to twelve.
Example 2. The long hand is at 7 and the short hand is just past 8. What is the time?
The long hand at 7 means 7 × 5 = 35 minutes, so the time is 8:35, which is also 25 minutes to 9.
Example 3. If March 1 is a Monday, what day is March 15?
March 8 is a Monday, and 7 days later March 15 is a Monday as well.
Example 4. How many days are there from April 10 to April 25?
25 − 10 = 15 days.
7. Practice
- Write 2:05 and 6:50 in words.
- What time is quarter to seven, in figures?
- How many minutes are there in a quarter of an hour?
- Is 7 AM before or after school assembly? Is 7 PM before or after dinner?
- How many days has September? How many has August?
- How many days does February have in a leap year?
- If June 3 is a Wednesday, what day is June 17?
8. Answers
- 2:05 is five minutes past two. 6:50 is ten minutes to seven.
- 6:45.
- 15 minutes.
- 7 AM is before assembly; 7 PM is after dinner.
- September has 30 days and August has 31.
- 29 days.
- June 10 is a Wednesday and June 17 is a Wednesday too, since the weekday repeats every 7 days.
9. Summary
- The short hand shows the hour, the long hand the minutes, and each clock number is worth 5 minutes.
- Quarter past is 15, half past is 30, quarter to is 45 minutes past the previous hour.
- Past 30 minutes it is clearer to count to the next hour: 9:50 is 10 to 10.
- AM is midnight to noon and PM is noon to midnight.
- Seven months have 31 days, four have 30, and February has 28 or 29.
- A leap year comes every four years and has 366 days.
- The same weekday returns every 7 days, which settles most calendar questions.
