Dates / Time Measurement
Time Measurement
Convert between days, weeks, months, and years. Understand leap years, decades, and centuries. Grades 4–5.
Time Unit Reference Table
7 days = 1 week
14 days = 2 weeks (fortnight)
~30 days = 1 month (average)
4 weeks ≈ 1 month
52 weeks = 1 year
12 months = 1 year
365 days = 1 year (common)
366 days = 1 leap year
10 years = 1 decade
100 years = 1 century
1000 years = 1 millennium
Leap Year Rules
Rule 1: Divisible by 4
Most years divisible by 4 are leap years. Examples: 2020, 2024, 2028 ✓
Exception: Century years (÷ 100) are NOT leap years...
1700, 1800, 1900 were NOT leap years even though divisible by 4.
Exception to the exception: Divisible by 400 ARE leap years
2000 WAS a leap year (divisible by 400). 2100 will NOT be.
Conversion Practice — Key Patterns
Weeks → Days
Multiply by 7. Example: 6 weeks = 6 × 7 = 42 days
Days → Weeks
Divide by 7 (with remainder). Example: 25 days = 3 weeks and 4 days
Years → Months
Multiply by 12. Example: 3 years = 3 × 12 = 36 months
Decades / Centuries
Decade = 10 years. Century = 100 years. Example: 2.5 centuries = 250 years
Practice Drills
20
Example: 7 × 3