Tick Tick Tick

What is time?
Time helps us know when things happen and how long they take. We use clocks and calendars to measure time.

Units of time
There are basic units you should know:

• Second — smallest common unit. 60 seconds = 1 minute.
• Minute — 60 seconds. 60 minutes = 1 hour.
• Hour — 60 minutes. 24 hours = 1 day.
• Day / Week / Month / Year — 1 day = 24 hours, 1 week = 7 days, months have 28–31 days, 1 year = 12 months.

Reading an analog clock
An analog clock has two main hands: the hour hand (short) and the minute hand (long). Sometimes a thin second hand moves fastest.

• When the minute hand points to 12, we say "o'clock" (for example, 4:00).
• Minute marks around the clock count by 5s: 1 = 5 minutes, 2 = 10 minutes, 3 = 15 minutes (a quarter past), 6 = 30 minutes (half past), 9 = 45 minutes (a quarter to the next hour).
• The hour hand shows the hour. If it is between two numbers, the time is after the lower number and before the higher one (for example, if the hour hand is between 3 and 4 and the minute hand is on 6, it is 3:30).

AM and PM
The day is divided into two 12-hour periods. AM (ante meridiem) is from midnight to noon. PM (post meridiem) is from noon to midnight. For example, 7:00 AM is morning; 7:00 PM is evening.

Finding elapsed time (how long something lasts)
To find elapsed time, subtract the start time from the end time. If minutes in the end time are fewer than minutes in the start time, borrow 1 hour (60 minutes) and then subtract. You can also count forward on a timeline by hours and minutes.

Tips for children

• Count minute marks by fives to read minutes quickly.
• Use a number line (timeline) for adding and subtracting time.
• Practice common phrases: o'clock, half past, quarter past, quarter to.

A clock helps us know the time. An analog clock has several important parts. Knowing these parts makes it easy to read time correctly.

• Clock face (dial): The round surface that shows the numbers 1 to 12. It is divided into 12 equal parts called hours, and each hour is further divided into 5 small parts for minutes.
• Hour hand: The shorter, thicker hand. It shows the hour. It moves slowly and sits between two numbers when it is part way through an hour (for example, between 3 and 4 at 3:30).
• Minute hand: The longer hand. It shows minutes. Every number on the dial (1 to 12) stands for 5 minutes when reading the minute hand (for example, 1 = 5 minutes, 2 = 10 minutes, …, 12 = 0 or 60 minutes).
• Second hand: A thin hand that moves quickly around the dial. It counts seconds. Not all clocks have a moving second hand (some may not show it or have a digital display).
• Center or pivot: The point in the middle where all hands are fixed and rotate from.
• Ticks or minute markings: Small lines around the edge for each minute (60 ticks). Longer marks often show the five-minute steps.
• Frame and glass: The round rim and cover that protect the clock face and hands.
• AM and PM: On a 12-hour clock we use AM (midnight to noon) and PM (noon to midnight) to know which half of the day it is.

How the hands move (simple view):

• Minute hand: moves one small step each minute and completes one full turn in 60 minutes.
• Hour hand: moves slowly and completes one full turn in 12 hours. It moves as the minutes pass (so at 3:30 the hour hand is halfway between 3 and 4).
• Second hand: moves one step each second and completes a full turn in 60 seconds.

Reading the time: Look at the hour hand first (which hour or between which two hours), then read the minute hand (count ticks or use the 5-minute numbers), then read seconds if needed.

An analogue clock has a circular face numbered 1 to 12, a short hour hand and a long minute hand (and sometimes a second hand). Reading time means finding the hour and the minutes shown by the two hands.

Steps to read time:

• Look at the hour hand (short hand). It points to the current hour or is between two numbers when the hour is partway through.
• Look at the minute hand (long hand). Each small mark between numbers = 1 minute. Each numbered mark (1 to 12) equals 5 minutes because 12 marks × 5 = 60 minutes.
• If the minute hand is on a number, multiply that number by 5 to get minutes. If it is between numbers, count the small marks from 12 to the minute hand.
• Say the time as “hour : minutes”. If minutes are 0, say “o’clock”. If minutes are more than 30 you can also say minutes to the next hour (for example, 2:50 = 10 to 3).

Special names to remember:

• Quarter past = 15 minutes past the hour (e.g., 4:15).
• Half past = 30 minutes past the hour (e.g., 4:30).
• Quarter to = 15 minutes to the next hour (e.g., 4:45 is quarter to 5).

Tips:

• When the minute hand is on 12, read the hour shown by the hour hand and say “o’clock”.
• If the minute hand has passed 12, the hour hand moves slightly past the hour number; the hour part of the time is the smaller number it has passed.
• To say time 'to' the next hour: subtract the minutes from 60 and name the next hour (e.g., 60 − 50 = 10, so 2:50 = 10 to 3).

AM and PM: Add AM for morning times (midnight to noon) and PM for afternoon/evening (noon to midnight) when needed.

A digital clock shows time in numbers using the format HH:MM (hours and minutes). To read a digital clock, read the hour (HH) first, then the minutes (MM). Many clocks also show AM or PM to tell whether it is morning or afternoon.

Key ideas:

• HH = hours (01 to 12 for 12-hour clocks, 00 to 23 for 24-hour clocks). A leading zero is used for single-digit hours (for example, 07).
• MM = minutes (00 to 59). If minutes are less than 10, we often say “oh” before the minute (e.g., 05:07 is read “seven oh seven”).
• AM (ante meridiem) means before midday (morning). PM (post meridiem) means after midday (afternoon/evening).
• To find elapsed time use minutes and hours together by converting hours to minutes when needed.

How to read examples and special cases:

• 07:30 → read as “seven thirty” or “half past seven” (30 minutes past the hour).
• 03:05 → read as “three oh five”.
• 12:00 → read as “twelve o’clock”. If it is noon write 12:00 PM; midnight can be shown as 12:00 AM or 00:00 on a 24-hour clock.
• 14:20 (24-hour clock) → read as “two twenty PM”.

Tips for students:

• Always say the hour first, then the minutes, then AM or PM if given.
• If you must calculate time passed, convert hours to minutes (1 hour = 60 minutes), do the subtraction or addition in minutes, then convert back to hours and minutes.
• Compare a digital time with an analog clock by imagining where the hour and minute hands would point: the minutes show how far around the clock the minute hand is (e.g., 15 → quarter past, 30 → half past).

What AM and PM mean
AM stands for ante meridiem (Latin) meaning "before noon". PM stands for post meridiem meaning "after noon".

Which hours are AM and which are PM?
• AM: 12:00 midnight (12:00 AM) up to 11:59 in the morning (11:59 AM).
• PM: 12:00 noon (12:00 PM) up to 11:59 at night (11:59 PM).

How to read a time with AM or PM
When you see a time like 7:30 AM, it means 30 minutes after seven in the morning. When you see 7:30 PM, it means 30 minutes after seven in the evening.

Common confusions and an easy rule
• 12:00 noon is 12:00 PM (midday).
• 12:00 midnight is 12:00 AM (start of the day).
Tip to remember: times from 12:00 midnight until before 12:00 noon are AM; times from 12:00 noon until before 12:00 midnight are PM.

Relation to the 24-hour clock (simple idea)
Some clocks use 0–23 hours. To change between 24-hour and 12-hour (AM/PM) formats, you use simple rules (see formulas below).

What is elapsed time / duration?
Elapsed time (or duration) is the amount of time that passes between a start time and an end time. For example, if a class starts at 9:15 and ends at 10:00, the elapsed time is 45 minutes.

Simple rule
Duration = End time − Start time

Ways to find duration

1. Using a number line or timeline: Mark the start time on the line and then count forward to the end time in steps (hours or minutes). Add the steps to get the total duration.
2. Using a clock face: Move the minute and hour hands from the start time to the end time. Count how many minutes and hours you moved.
3. Using subtraction of hours and minutes: Subtract the start time from the end time. If the minutes in the end time are less than the minutes in the start time, borrow 1 hour (60 minutes) from the end hour, add 60 to end minutes, then subtract.

Tips for working with hours and minutes

• 1 hour = 60 minutes.
• To convert hours to minutes: multiply by 60. Example: 2 hours = 2 × 60 = 120 minutes.
• To convert minutes to hours and minutes: divide by 60. Example: 125 minutes = 2 hours 5 minutes (because 125 ÷ 60 = 2 remainder 5).
• If the period crosses noon or midnight, treat the times normally; just remember AM and PM so you subtract correctly.

Step-by-step subtraction method (when end minutes >= start minutes)

1. Write end time and start time in hours:minutes form.
2. Subtract minutes: end minutes − start minutes.
3. Subtract hours: end hours − start hours.
4. Combine hours and minutes as the duration.

Step-by-step if end minutes < start minutes

1. Borrow 1 hour (60 minutes) from the end hours: decrease end hours by 1 and add 60 to end minutes.
2. Now subtract minutes and hours as above.

What is a calendar? A calendar is a system for organizing days into weeks, months and years so we can keep track of dates, plan events and know which day of the week a date falls on.

Key parts

• Week: 7 days (Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday).
• Month: 12 months in a year: January, February, March, April, May, June, July, August, September, October, November, December.
• Year: Usually 365 days; in a leap year 366 days.

Days in each month

• January – 31
• February – 28 (29 in a leap year)
• March – 31
• April – 30
• May – 31
• June – 30
• July – 31
• August – 31
• September – 30
• October – 31
• November – 30
• December – 31

Knuckle trick to remember month lengths: Make a fist and count months on the knuckles and gaps. Each knuckle = 31 days, each gap = 30 (or 28/29 for February). Start with January on the first knuckle.

Leap year rule (simple): Most years divisible by 4 are leap years (February has 29 days). A more complete rule (useful for later grades): if a year is divisible by 100 it must also be divisible by 400 to be a leap year.

Finding the day for a new date: Days of the week repeat every 7 days. To find the day of the week for a date when you know another date's weekday, count how many days apart the dates are, then divide that difference by 7. The remainder tells how many weekdays to move forward (or backward if counting earlier). Example idea: if 1 March is Monday and March has 31 days, 1 April is 31 days later → 31 mod 7 = 3 → Monday + 3 days = Thursday.

Using a calendar: A calendar page shows weeks as rows and weekdays as columns so you can see the weekday for any date. Practice reading and filling simple calendars helps in planning and understanding weekly patterns.

Practical Activities and Exercises help Class 4 students learn how to read clocks, tell time, measure durations and plan daily activities using hands-on practice. Use simple, step-by-step tasks: make a paper clock, move hour and minute hands to show given times, match digital and analog times, use a stopwatch to count seconds, and fill timetables for a day.

Key ideas to emphasise:

• Reading an analog clock: the short hand shows hours and the long hand shows minutes. Each number on the clock stands for 5 minutes (1 = 5 min, 2 = 10 min, …, 12 = 60/0 min).
• Common expressions: o'clock (3:00), half past (3:30), quarter past (3:15), quarter to (2:45).
• Counting minutes: move the minute hand forward or backward in steps of 1 minute or 5 minutes to find the time difference.
• Elapsed time (how long something takes): find the difference between start and end times by counting on the clock or converting times to minutes and subtracting.
• Daily scheduling and estimation: use timetables and simple surveys to record and compare how much time is spent on sleep, study, play and other activities.

Practical classroom activities: make paper plate clocks, play “What time is it?” matching games, time scavenger hunts (record times when specific actions happen), use a stopwatch for short experiments (how long to run 100 steps), and create simple timetables and bar/pie charts of daily activities.