Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

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Performance objectives

• Convert between hours, minutes, and seconds.
• Calculate the duration of an event.
• Read and interpret calendar dates.
• Solve word problems involving time.
• Use analogue and digital clocks.

Lesson summary

Time and calendars are fundamental parts of our everyday lives. Understanding how to tell time, read calendars, and calculate durations is crucial for planning our days, managing schedules, and understanding important events in our lives and in the history of South Africa. From knowing when to catch the Putco bus to school, to understanding the dates of national holidays like Freedom Day or Youth Day, time and calendars help us stay organized and connected to the world around us.

Lesson notes

2.1 Units of Time: The basic units of time are seconds, minutes, hours, days, weeks, months, and years. It's important to understand the relationships between these units: 60 seconds = 1 minute 60 minutes = 1 hour 24 hours = 1 day 7 days = 1 week Approximately 4 weeks = 1 month (There are typically between 4 and 5 weeks in a month) 12 months = 1 year 365 days = 1 year (Normal year) 366 days = 1 leap year A leap year occurs every four years. It is a year in which an extra day is added to February (29 days instead of 28). A leap year helps to keep our calendar aligned with the Earth's orbit around the sun. 2.2 Analogue and Digital Clocks: Analogue Clock: This type of clock has a face with numbers 1 to 12 and two hands: the hour hand (shorter) and the minute hand (longer). The second hand (if present) is usually the thinnest hand. To tell time, you need to look at the position of both hands. Remember each number on the clock face represents 5 minutes when read for the minutes.

Digital Clock: This type of clock displays the time using digits. It usually shows the hour and minutes separated by a colon (e.g., 10:30). Digital clocks can also show seconds. 2.3 Calculating Duration: Duration is the amount of time that passes between two points in time. To calculate the duration of an event, you need to know the start time and the end time.

Example 1: A soccer game starts at 3:00 PM and ends at 4:45 P

M. How long did the game last?

Start time: 3:00 PM End time: 4:45 PM Duration: 1 hour and 45 minutes Example 2: Sipho starts reading his book at 7:15 AM and finishes at 8:30 A

M. How long did Sipho read?

Start time: 7:15 AM End time: 8:30 AM To find the duration, subtract the start time from the end time.

Hours: 8 - 7 = 1 hour Minutes: 30 - 15 = 15 minutes Duration: 1 hour and 15 minutes Example 3: Thandi started baking cookies at 10:50 AM and finished at 11:25 A

M. How long did she bake?

Start time: 10:50 AM End Time: 11:25 AM Since we can't easily subtract 50 minutes from 25 minutes, we need to "borrow" an hour from the 11. 11:25 AM becomes 10:85 AM (because 1 hour = 60 minutes, and we add it to the 25 minutes)

Now we can subtract: 10:85 - 10:50 = 0:35 Duration: 35 minutes 2.4 Using Calendars: A calendar is a tool used to organize days, weeks, months, and years. It shows the dates of the month and the days of the week. Calendars are useful for planning events, keeping track of appointments, and remembering important dates. A typical calendar will indicate the days of the week (Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday) across the top. The calendar month will be displayed underneath these headers. Important dates like public holidays are often indicated on a calendar, sometimes with an icon or a specific color.

Example 4: If today is the 8th of August, and it's a Tuesday, what day of the week will it be on the 22nd of August? There are 14 days between the 8th and the 22nd (22 - 8 = 14). There are two weeks in 14 days (14 / 7 = 2). Since there are exactly two weeks, the 22nd of August will be the same day of the week as the 8th of August, which is Tuesday.

Example 5: How many days are there between the 5th of March and the 20th of March in a non-leap year? Subtract the first date from the second date: 20 - 5 = 15 days. Guided Practice (With Solutions)

Question 1: A taxi ride starts at 8:10 AM and ends at 8:55 A

M. How long was the taxi ride?

Solution: Start time: 8:10 AM End time: 8:55 AM Minutes: 55 - 10 = 45 minutes The taxi ride lasted 45 minutes.

Commentary: Here we simply subtract the starting minutes from the ending minutes because the hours were the same.

Question 2: Lerato starts her homework at 4:30 PM and finishes at 6:00 P

M. How long did Lerato spend doing her homework?

Solution: Start time: 4:30 PM End time: 6:00 PM Hours: 6 - 4 = 2 hours Since there are 30 minutes to consider, we need to subtract this: 2 hours - 30 minutes = 1 hour and 30 minutes Lerato spent 1 hour and 30 minutes doing her homework.

Commentary: In this case, we calculated the difference in hours, and then adjusted for the minutes.

Question 3: A movie starts at 2:45 PM and is 1 hour and 30 minutes long. What time does the movie end?

Solution: Start time: 2:45 PM Duration: 1 hour and 30 minutes Add the hour: 2:45 PM + 1 hour = 3:45 PM Add the minutes: 3:45 PM + 30 minutes = 4:15 PM The movie ends at 4:15 P

M. Commentary: Here, we added the duration to the start time to find the end time. It's important to add the hours and minutes separately.

Question 4: Today is Wednesday, the 10th of May. What day of the week will it be on the 24th of May?

Solution: Calculate the number of days between the two dates: 24 - 10 = 14 days.

Determine the number of weeks: 14 days / 7 days/week = 2 weeks. Since it is an exact number of weeks, the day of the week will be the same.

Therefore, the 24th of May will be a Wednesday.

Commentary: Remembering that days of the week repeat every 7 days is key here.