Time

Time Measurement

We measure time in seconds, minutes, hours, days, weeks, months and years with clocks and calendars.

Day, Hours, Minutes

A day has 24 hours but a clock has numbers only from 1 to 12 written on it. This means that there will be two rounds of 12 hours in a day (A.M. & P.M.). Time from 12:00 in the midnight to 11:59 in the morning is referred to as 'A.M'. Time from 12:00 in the afternoon to late night 11:59 is referred to as 'P.M'.

An hour consists of 60 minutes. 

A minute consists of 60 seconds.

Measurement of Time Using a Clock

1. Analog Clock or the 12-hour clock

We measure and define what time of the day it is using clocks. A clock in general has 12 numbers written on it, from 1 to 12. It has an hour hand and a minute hand. Some clocks have a third hand as well. It shows time in seconds and is the fastest-moving hand. The time is usually based on a 12-hour clock.

The hour hand, the shorter of the two hands, completes 1 rotation (360°) in 12 hours in a normal 12-hour analog. The minute hand, the longer hand, completes 1 rotation through 360° in 60 minutes.

To read the clock below, we first need to look at the hour hand. The hour hand is between  1 and 2, so it is after 1 o'clock but not yet 2 o'clock.

So, the hour is 1. Next, we look at the minute hand. The minute hand starts pointing straight up at the 12 for 0 minutes.
When counting minutes, the distance between each tick mark represents 1 minute. Each number on the clock represents 5 minutes, with a total of 60] minutes in each hour.

https://www.cuemath.com/measurement/time/

https://www.splashlearn.com/math-vocabulary/time/time

https://www.khanacademy.org/math/cc-2nd-grade-math/x3184e0ec:money-and-time/cc-2nd-money/a/money-and-time-faq