Learn on PengiSaxon Math, Intermediate 4Chapter 2: Lessons 11–20, Investigation 2

Lesson 19: Elapsed Time Problems, Activity Finding Elapsed Time

In this Grade 4 lesson from Saxon Math Intermediate 4, students learn to read analog clocks using the hour and minute scales, write time in digital form using a.m. and p.m. notation, and express time in words such as "half past," "quarter after," and "quarter to." The lesson also introduces elapsed time, teaching students to calculate the difference between two points in time by counting hours and minutes separately and then adding them together.

Section 1

📘 Elapsed Time Problems

New Concept

Elapsed time is the difference between two points in time.

What’s next

Next, you'll use this concept to solve problems by finding the time that passes between a start and an end time.

Section 2

Digital Form

Property

To write the time of day, we write the hour followed by a colon. Then we write two digits to show the number of minutes after the hour. We use the abbreviations a.m. for the 12 hours before noon and p.m. for the 12 hours after noon.

Examples

  • A quarter to nine in the evening is 15 minutes before 9 p.m., which is written as 8:458:45 p.m.
  • Ten minutes past seven in the morning is written as 7:107:10 a.m.
  • Midnight is the very start of a new day, so we write it as 12:0012:00 a.m.

Explanation

Think of digital form as the universal code for time! The numbers before the colon pinpoint the hour, while the two digits after tell you the exact minute. Using 'a.m.' signals morning adventures before noon, and 'p.m.' marks all your fun from noon until midnight. It’s the clearest way to avoid showing up late!

Section 3

Elapsed time

Property

Elapsed time is the difference between two points in time.

Examples

  • A party starts at 2:002:00 p.m. and ends at 4:304:30 p.m. The elapsed time is 2 hours and 30 minutes.
  • If you start a video game at 6:006:00 p.m. and stop at 7:157:15 p.m., you played for 1 hour and 15 minutes.
  • From 8:008:00 a.m. to 10:4510:45 a.m. is a total of 2 hours and 45 minutes of time passed.

Explanation

Ever wonder how long a movie really is or how much time you have to finish your homework? That's elapsed time! It’s just a cool way of saying 'how much time has passed' from a start point to an end point. You just count the full hours first, then add up the remaining minutes to get your answer.

Section 4

Reading Math

Property

We can write or say the time in different ways:
10:4310:43
• 43 minutes after 10:0010:00
• 17 minutes to 11:0011:00

Examples

  • The time 3:453:45 p.m. can also be expressed as 'a quarter to four in the afternoon.'
  • The time 6:156:15 a.m. is often called 'a quarter after six in the morning.'
  • If a clock shows 5:505:50 p.m., you can also say it's 'ten minutes to six in the evening.'

Explanation

Time is a master of disguise! The same moment can be described in multiple ways, like saying '8:458:45' or 'a quarter to 9.' Knowing these different phrases is like being fluent in the secret languages of a clock. It helps you understand what anyone means, no matter how they say it, and makes you a true time wizard.

Book overview

Jump across lessons in the current chapter without opening the full course modal.

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Chapter 2: Lessons 11–20, Investigation 2

  1. Lesson 1

    Lesson 11: Addition Word Problems with Missing Addends

  2. Lesson 2

    Lesson 12: Missing Numbers in Subtraction

  3. Lesson 3

    Lesson 13: Adding Three-Digit Numbers, Activity Adding Money

  4. Lesson 4

    Lesson 14: Subtracting Two-Digit and Three-Digit Numbers, Missing Two-Digit Addends

  5. Lesson 5

    Lesson 15: Subtracting Two-Digit Numbers with Regrouping, Activity Subtracting Money

  6. Lesson 6

    Lesson 16: Expanded Form, More on Missing Numbers in Subtraction

  7. Lesson 7

    Lesson 17: Adding Columns of Numbers with Regrouping

  8. Lesson 8

    Lesson 18: Temperature, Activity Measuring Temperature

  9. Lesson 9Current

    Lesson 19: Elapsed Time Problems, Activity Finding Elapsed Time

  10. Lesson 10

    Lesson 20: Rounding

  11. Lesson 11

    Investigation 2: Units of Length and Perimeter, Activity Estimating the Perimeter

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

📘 Elapsed Time Problems

New Concept

Elapsed time is the difference between two points in time.

What’s next

Next, you'll use this concept to solve problems by finding the time that passes between a start and an end time.

Section 2

Digital Form

Property

To write the time of day, we write the hour followed by a colon. Then we write two digits to show the number of minutes after the hour. We use the abbreviations a.m. for the 12 hours before noon and p.m. for the 12 hours after noon.

Examples

  • A quarter to nine in the evening is 15 minutes before 9 p.m., which is written as 8:458:45 p.m.
  • Ten minutes past seven in the morning is written as 7:107:10 a.m.
  • Midnight is the very start of a new day, so we write it as 12:0012:00 a.m.

Explanation

Think of digital form as the universal code for time! The numbers before the colon pinpoint the hour, while the two digits after tell you the exact minute. Using 'a.m.' signals morning adventures before noon, and 'p.m.' marks all your fun from noon until midnight. It’s the clearest way to avoid showing up late!

Section 3

Elapsed time

Property

Elapsed time is the difference between two points in time.

Examples

  • A party starts at 2:002:00 p.m. and ends at 4:304:30 p.m. The elapsed time is 2 hours and 30 minutes.
  • If you start a video game at 6:006:00 p.m. and stop at 7:157:15 p.m., you played for 1 hour and 15 minutes.
  • From 8:008:00 a.m. to 10:4510:45 a.m. is a total of 2 hours and 45 minutes of time passed.

Explanation

Ever wonder how long a movie really is or how much time you have to finish your homework? That's elapsed time! It’s just a cool way of saying 'how much time has passed' from a start point to an end point. You just count the full hours first, then add up the remaining minutes to get your answer.

Section 4

Reading Math

Property

We can write or say the time in different ways:
10:4310:43
• 43 minutes after 10:0010:00
• 17 minutes to 11:0011:00

Examples

  • The time 3:453:45 p.m. can also be expressed as 'a quarter to four in the afternoon.'
  • The time 6:156:15 a.m. is often called 'a quarter after six in the morning.'
  • If a clock shows 5:505:50 p.m., you can also say it's 'ten minutes to six in the evening.'

Explanation

Time is a master of disguise! The same moment can be described in multiple ways, like saying '8:458:45' or 'a quarter to 9.' Knowing these different phrases is like being fluent in the secret languages of a clock. It helps you understand what anyone means, no matter how they say it, and makes you a true time wizard.

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 2: Lessons 11–20, Investigation 2

  1. Lesson 1

    Lesson 11: Addition Word Problems with Missing Addends

  2. Lesson 2

    Lesson 12: Missing Numbers in Subtraction

  3. Lesson 3

    Lesson 13: Adding Three-Digit Numbers, Activity Adding Money

  4. Lesson 4

    Lesson 14: Subtracting Two-Digit and Three-Digit Numbers, Missing Two-Digit Addends

  5. Lesson 5

    Lesson 15: Subtracting Two-Digit Numbers with Regrouping, Activity Subtracting Money

  6. Lesson 6

    Lesson 16: Expanded Form, More on Missing Numbers in Subtraction

  7. Lesson 7

    Lesson 17: Adding Columns of Numbers with Regrouping

  8. Lesson 8

    Lesson 18: Temperature, Activity Measuring Temperature

  9. Lesson 9Current

    Lesson 19: Elapsed Time Problems, Activity Finding Elapsed Time

  10. Lesson 10

    Lesson 20: Rounding

  11. Lesson 11

    Investigation 2: Units of Length and Perimeter, Activity Estimating the Perimeter