A standard year, without a leap year, consists of 52 weeks. A week is a time unit consisting of seven days. There 365 days in a year, 52 weeks in a year and 12 months in a year. Year’s that begin on a Thursday and leap years that begin on a Wednesday have 53 weeks. In most parts of the world the week is the accepted time period used for work and rest days schedule.
There are 52 complete weeks in a year. The year has 365 days, leaving one extra day. A leap year has 366 days, adding a second extra day. This makes 52 1/7 weeks in a normal year and 52 2/7 weeks in a leap year.
If you mean seven days from Sunday till Saturday, then no year will have more than 52 weeks. But if a week for you is a separate line or column in the calendar, then there may be up to 54 weeks in a year.
The schedule for public schools lies with each particular school district of which it is a part; as such, the total number of weeks in a school year can vary considerably. The number of weeks in a school year for a private school is set by the school in question.