Reading a calendar
A calendar shows the days of each month arranged in weeks. Each row is one week (7 days) and each column is a day of the week.
Months and their days
| Month | Days |
|---|---|
| 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 |
A rhyme helps: "Thirty days has September, April, June and November…"
A knuckle trick also works: make two fists. Every knuckle is a 31-day month, and every dip between knuckles is a shorter month.
Leap years
A leap year has 366 days because February gets a 29th day. Leap years usually come every 4 years (2024, 2028, 2032). Century years are leap years only if they divide by 400, so 2000 was a leap year but 2100 won’t be.
Counting days
Days between two dates: Count on. From March 25 to April 3:
- March 25 → March 31 = 6 days
- March 31 → April 3 = 3 days
- Total: 9 days later.
Inclusive counting: If a camp runs from July 8 to July 12 inclusive, count both ends: 8, 9, 10, 11, 12 = 5 days. (12 − 8 = 4, then add 1.)
Finding a day of the week
Days repeat every 7. If May 1 is a Tuesday, then May 8, 15, 22 and 29 are also Tuesdays.
Example: If May 1 is a Tuesday, what day is May 20?
May 15 is a Tuesday. May 20 is 5 days later → Sunday.
Making a schedule
A schedule lists events with their times or dates. To build one:
- List the events and how long each takes.
- Put them in order.
- Check for overlaps and travel time.
| Time | Activity |
|---|---|
| 8:30 | Arrive at school |
| 8:45 | Math |
| 10:00 | Recess |
| 10:15 | Science |
Worked examples
Example 1: How many days in June and July together?
30 + 31 = 61 days.
Example 2: A library book borrowed on October 12 is due in 21 days. When is it due?
12 + 21 = November 2 (October has 31 days, so October 33 = November 2).
Example 3: Is 2032 a leap year?
2032 ÷ 4 = 508. Yes.
Common mistakes
- Forgetting which months have 30 days.
- Off-by-one errors: forgetting to add 1 when counting inclusively.
- Assuming every 4th year is always a leap year, including century years.
Try it yourself
- How many days are in April?
- If today is Friday, what day is it in 10 days?
- A festival runs from August 3 to August 9 inclusive. How many days?
- How many weeks are in 84 days?
Answers: 1) 30 2) Monday 3) 7 4) 12
Quick recap
- A calendar organizes days into weeks and months.
- Know the days in each month; a leap year has 366 days.
- Count carefully, adding 1 for inclusive counts.