194How long is a month?
To help us calculate with time, it’s
useful to know how many days
there are in each month.
Most of the months of the year
have 30 or 31 days. February
usually has 28 days, except in
a leap year, when there are 29.Dates
As well as seconds, minutes, and hours, we can measure time
in units called days, weeks, months, and years. We use these
units to measure periods of time that are longer than 24 hours.MEASUREMENT • DATES MEASUREMENT • DATESDays
There are 24 hours in a day. A day is the length
of time it takes for Earth to spin once on its axis.Weeks
Days are grouped into a unit of time called
weeks. There are 7 days in a week. This might
be because it’s a quarter of the cycle of the Moon
(the time between one full Moon and the next).Months
There are between 28 and 31 days in a
month. Months may have come from the lunar
calendar at first, but have changed over time.
Not all months have the same number of days.Years
There are 365 days in a year. This is the same
as 52 weeks or 12 months. A year is the length of
time it takes for Earth to orbit the Sun once.January31 daysFebruary28 or 29 daysMarch31 daysApril30 days
May31 daysJune30 days
July31 days
August31 daysSeptember30 daysOctober31 daysNovember30 daysDecember31 daysLook at these knuckles.
The first 7 knuckles and
the dips between them are
labelled with a month.The months that
sit on a knuckle are
31 days long: January,
March, May, July,
August, October,
and December.All the months,
except February,
that sit in a dip
between two knuckles
are 30 days long:
April, June, September,
and November.One year is 365 days
long, except on
a leap year when
there are 366 days.One year is how
long it takes for
Earth to orbit
the SunOne day is
one full spin
of EarthOne week is one-quarter of the time
between one full Moon and the nextOne month
is based on
the cycle of
the Moon194-195_Dates.indd 194 11/03/2016 16:24