Grade 4

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Converting Units of Time


Time is an important part of our daily lives. We follow time to perform daily activities, monitor events, and organize our schedules. In math, understanding how to convert units of time is fundamental. Converting units of time means converting one measure of time into another equivalent measure. For example, converting hours into minutes or seconds into minutes. In this lesson, we'll learn how to convert between different units of time, understand why it's important, and work through lots of examples.

Understanding units of time

Time is measured using different units. The most common units of time used in daily life and study are:

  • Seconds
  • Minutes
  • Hours
  • Day
  • Weeks
  • Month
  • Year

Each of these units measures different lengths of time. For example, seconds are a smaller unit, while hours are larger. To understand how they relate, let's look at some basic conversions:

  • 1 minute = 60 seconds
  • 1 hour = 60 minutes
  • 1 day = 24 hours
  • 1 week = 7 days
  • 1 month = approximately 30 days
  • 1 year = 12 months

Why convert units of time?

Converting units of time is extremely useful because it allows you to:

  • Easily compare different time intervals.
  • Plan the event effectively.
  • Understand the duration when looking at timelines and schedules.
  • Calculate age, count days until an event, or find out how long a task will take.

Basic conversions: minutes and seconds

Let's start with the conversion between seconds and minutes:

Since 1 minute = 60 seconds, you must multiply or divide by 60 to convert between these units. See some examples below:

Example 1: Convert 180 seconds to minutes.

180 seconds ÷ 60 = 3 minutes

The conversion tells us that 180 seconds is equal to 3 minutes.

Example 2: Convert 2.5 minutes into seconds.

2.5 minutes × 60 = 150 seconds

This means that 2.5 minutes is equal to 150 seconds.

Visual example: minutes and seconds

Consider converting 2 minutes to seconds:

_____ ______ ______ ______ ______ ______ |_____|_____|_____|_____|_____|_____| ....(each tick represents 10 seconds)

Here, each small segment represents 10 seconds. 6 segments make a minute (10 × 6 = 60) seconds, so two such groups represent 2 minutes.

Converting hours and minutes

Now we will convert between hours and minutes. Remember that 1 hour = 60 minutes.

Example 1: Convert 4 hours to minutes.

4 hours × 60 = 240 minutes

Therefore, 4 hours is equal to 240 minutes.

Example 2: Convert 150 minutes into hours.

150 minutes ÷ 60 = 2.5 hours

This conversion shows that 150 minutes is equal to 2.5 hours.

Visual example: hours and minutes

Consider transforming a scene from 2 hours to minutes:

______________ ___________________________ |______________|___________________________| (60 minutes) (60 minutes)

Each long block above represents 1 hour (made up of 60 minutes), and together they represent 2 hours, which equals 120 minutes.

Converting days and hours

Now, let's convert days into hours. Remember that 1 day = 24 hours.

Example 1: Convert 3 days to hours.

3 days × 24 = 72 hours

This means that 3 days is equal to 72 hours.

Example 2: Convert 96 hours to days.

96 hours ÷ 24 = 4 days

Here 96 hours has been converted to 4 days.

Visual example: days and hours

Consider an example of converting 2 days to hours:

___________________ ___________________ |___________________|___________________| (24 hours) (24 hours)

Each block represents one day of 24 hours, resulting in two days of 48 hours each.

Converting days and weeks

While converting weeks to days, keep in mind that 1 week = 7 days.

Example 1: Convert 2 weeks to days.

2 weeks × 7 = 14 days

From this we know that 2 weeks is equal to 14 days.

Example 2: Convert 21 days to weeks.

21 days ÷ 7 = 3 weeks

Thus, 21 days are converted into 3 weeks.

Visual example: weeks and days

Consider converting a week into days:

| Su | Mo | Tu | We | Th | Fr | Sa | _____________________________________

Each day of the week represents a complete cycle in the 7-day week.

Practice problems

Test your understanding of converting units of time with the following practice problems:

  1. Convert 5 minutes into seconds.
  2. How many hours are there in 720 minutes?
  3. If you have 48 hours, how many days will that be?
  4. Convert 18,000 seconds to hours and minutes.
  5. How many weeks are there in 31 days?

Try solving these questions, and check your answers:

  1. 5 minutes =
    5 × 60 = 300 seconds
  2. 720 minutes =
    720 ÷ 60 = 12 hours
  3. 48 hours =
    48 ÷ 24 = 2 days
  4. 18,000 seconds =
    18,000 ÷ 3600 = 5 hours and 18,000 % 3600 = 0 minutes
  5. 31 days =
    31 ÷ 7 = 4 weeks and 31 % 7 = 3 days

Conclusion

Converting units of time is an essential skill in math that makes it easier to manage and plan time effectively. By knowing how to convert seconds to minutes, minutes to hours, and so on, you can solve real-world problems more efficiently. Practice this skill by solving different types of conversion problems and understanding their application in different scenarios. Enjoy converting!


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