Spans of Time: Determining, Measuring, Converting

Lesson Plan - Get It!

Audio:

Everything you do is based on time.

The passage of time is measured by the movement of Earth, as you will see in a couple minutes.

How many units of time can you remember? On a sheet of paper, fill in the table below based on what you already know:

___ seconds = 1 minute

___ minutes = 1 hour

___ hours = 1 day

___ days = 1 week

___ months = 1 year

___ weeks = 1 year

___ days = 1 year

___ days = leap year

Watch a video to help you remember units of time. As you watch this Fredbot clip from Fredbot Learn Units of Time!, see how many of the units of time you remembered. Fill in any information from the video to complete the table as you watch (the relevant clip ends at 1:02):

• The time it takes Earth to travel around the sun is a year, or about 365 days.
• A leap year occurs every four years, which is 366 days.
• A year is divided into 12 months or 52 weeks.
• A week is seven days in a row.
• The length of time it takes Earth to spin around on its axis once is called a "day."
• A day is divided into 24 equal parts called "hours."
• Each hour in a day is divided into 60 equal lengths of time called "minutes."
• Each minute is divided into 60 seconds.

Time is measured using clocks and calendars. Time can be converted, or changed, into other units. To convert from a larger unit, such as a day, to a smaller unit, such as an hour, you will multiply. To convert from a smaller unit, such as seconds, to a larger unit, such as days, you will divide.

Example 1 How many hours are in 9 days?

You want to convert 9 days into hours. Days are larger than hours, so you will multiply since you are going from a larger unit to a smaller unit.

There are 24 hours in a day, so multiply 9 by 24. 9 x 24 = 216, so there are 216 hours in 9 days.

Example 2 How many minutes is 240 seconds?

You want to convert 240 seconds into minutes. Seconds are smaller than minutes, so you will divide since you are going from a smaller unit to a larger unit. There are 60 seconds in a minute, so divide 240 by 60, which is 4. So, 4 minutes is the same amount of time as 240 seconds.

If there is a remainder, it should be less than 60 seconds. Since 60 seconds equals a minute, the leftover time would be seconds.

Example 3 At the beginning of the lesson, you were asked the following problem:

Your family vacation to the waterpark takes 4 hours. How many seconds are in 4 hours?

You want to convert 4 hours to seconds. In the chart above, you will notice there is not a conversion for how many seconds are in an hour. You will have to use two steps to convert hours to seconds. Convert hours to minutes, then minutes to seconds.

First, convert 4 hours to minutes. Since you are converting a larger unit to a smaller unit, multiply. There are 60 minutes in an hour, so multiply 4 hours by 60. 4 x 60 = 240, so there are 240 minutes in 4 hours.

Next, convert 240 minutes to seconds. Since you are converting a larger unit to a smaller unit, multiply. There are 60 seconds in a minute, so multiply 240 minutes by 60. 240 x 60 = 14,400, so there are 14,400 seconds in 4 hours.

Discuss with a parent or teacher:

• What is the smallest unit of time in a day?
• How do you convert smaller units to larger units?
• How do you convert larger units to smaller units?

In the Got It? section, you will practice measuring and converting time while completing interactive practice.