A 'Leap Year' occurs every 4 years because the actual time that the Earth takes to travel around the Sun is 365¼ days  so after every 4 years we have an extra day, the 29th February, which is added to the year to ensure that the seasons are synchronized.
If a year is divisible by 4 it is a leap year. (except for some Century years)
The next leap years are 2016, 2020 and 2024 which also coincide with the years that
the Summer Olympics take place.

How many days are in each month?
30 days has September,
April, June and November.
All the rest have 31,
Except February alone,
Which has but 28 days clear
And 29 in each leap year.

Analogue Time  am/pm  The 12 Hour Clock
Analogue Time splits the day into two halves of 12 hours.
From midnight to midday  am  (Ante Meridiem  which is Latin for 'before noon'.)
From midday to midnight  pm (Post Meridiem  which is Latin for 'after noon'.)
This overcomes the problem that there are 2 times during the day when the hour is the same, which is why we must add 'am' or 'pm' to the time.

Digital Time  The 24 Hour Clock
Digital time uses the full 24 hours of a day  so there is no problem of having the same hour twice in a day (there is no 'am' or 'pm'). The day starts at midnight, 00:00 and counts
through in hours and minutes until one second before midnight, 23:59.
The 24hour clock always uses 4 digits.
7:35 am = 07:35 .... 9:21 am = 09:21 .... Midday = 12:00 .... 1:20 pm = 13:20 .... 7:35 pm = 19:35
(don't forget to include the zero for 07:35 and 09:21 etc)
To convert from Analogue to 24hour time  for any time after 12:59 pm just add 12.
(3.00pm becomes 3 + 12 = 15:00 ..... 5:30pm becomes 5 + 12 = 17:30)

'Past' and 'To' the hour
When using Analogue time, any minute up to 30 is said to be 'past' the hour that has already gone ... 09:26 would be '26 minutes past nine'. Any minute after 30 minutes is said to be 'to' the next hour ... 09:36 would be '24 minutes to 10'.

Halves and Quarters
If the minute hand is on 15 it is usual to say quarter past the previous hour.
If the minute hand is on 45 it is usual to say quarter to the next hour.
If the minute hand is on 30 it is usual to half past the previous hour.

