Telling time is very important.
Telling time helps us make plans, and live a good life.
We use a number of different units for time.
Units of time are different lengths of time that everyone agrees on.
Here are the most common units of time, from smallest to largest:
seconds
minutes
hours
days
weeks
months
years
Each unit can be used as building blocks for the other units.
For example, there are 60 seconds in 1 minute.
Imagine each second as a building block for creating 1 minute.
Here are all the conversion ratios between units of time:
Note: A month can either have 30 or 31 days, except for February.
February has 28 days. We add 1 day to February when it's the leap year.
Let's say you come across this problem:
Anna studies for school 3 hours a day this week. How many hours has Anna spent studying for school this week?
To figure out the answer to this, we think about our conversion ratio for weeks, days, and hours.
🌞 1 week is equal to 7 days.
👉 "3 hours a day this week" can be written as 3 hours x 7 days.
3 x 7 = 21
✅ Anna spent 21 hours studying for school this week.
Great work! 👏
Here's another problem.
How many minutes are there in 8 hours?
To figure out the answer, let's create a table.
Our table shows that there are 480 minutes in 8 hours.
You will learn more about converting time units in the next lesson.
There are even more units of time. Some are used for really long periods of time.
Decade is a period of 10 years.
Century means 100 years.
Millennium is a period of 1,000 years.
There are 10 decades in one century. 👍
A millennium is made up of 10 centuries. 👍
Each time unit is best used for a specific situation.
The time it takes to wink is expressed in seconds.
We use minutes to tell about the total time we spend brushing our teeth.
We also use minutes to describe the time it takes to go run a mile.
But the time spent for finishing a marathon is described using hours and minutes.
It takes days for a seed to sprout.
It takes months for a tomato plant to bear fruit.
It takes years for trees to grow tall.
😃 It's important to use the right unit of time. Imagine if we used hours to describe the time it takes for a tree to grow.
Instead of saying 7 years, we would say 61,320 hours! That wouldn't make much sense to us. 😌
Great work reviewing units of time!
Now, try the practice!