Lesson Notes By Weeks and Term v5 - Grade 5

Lesson Video

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Performance objectives

• Read analogue and digital clocks.
• Calculate time intervals in hours and minutes.
• Read temperatures on a Celsius thermometer.
• Solve practical problems involving temperature.
• Solve word problems with length, mass, and capacity.

Lesson summary

This week, we're focusing on time, temperature, and everyday measurement problems. These are crucial skills that you'll use every single day, whether it's planning your school day, understanding the weather forecast, or helping your family with shopping and cooking.

Think about it: How do you know when the taxi is coming? How do you decide what clothes to wear? How do you follow a recipe for your favourite malva pudding? All these involve understanding time, temperature, and measurement! Being confident with these skills allows you to be more independent, organized, and able to solve real-world problems.

Lesson notes

Time Understanding Analogue and Digital Clocks: An analogue clock has hands that point to numbers on a clock face. The short hand tells us the hour, and the long hand tells us the minutes. Remember, the hour hand moves a little bit towards the next hour as the minutes pass. A digital clock shows the time using numbers separated by a colon (:). The numbers to the left of the colon represent the hour, and the numbers to the right represent the minutes.

Calculating Time Intervals: To calculate the time interval between two times, we need to find the difference between them. We can do this by counting forward in hours and minutes. Remember that there are 60 minutes in an hour.

Example 1: Reading Clocks Analogue: The short hand is just past the 3, and the long hand is on the

6. What time is it?

Answer: 3:30 (or half past three).* Digital: The clock reads 07:

4

5. What time is it?

Answer: 7:45 (or quarter to eight).* Example 2: Calculating Time Intervals A soccer match starts at 3:15 PM and ends at 4:45 P

M. How long did the match last?

Step 1: From 3:15 PM to 4:00 PM is 45 minutes.

Step 2: From 4:00 PM to 4:45 PM is 45 minutes.

Step 3: Add the time intervals: 45 minutes + 45 minutes = 90 minutes.

Step 4: Convert 90 minutes to hours and minutes: 90 minutes = 1 hour and 30 minutes.

Answer: The soccer match lasted 1 hour and 30 minutes.

Example 3: More Complex Time Intervals Sipho starts his homework at 5:50 PM and finishes at 7:10 P

M. How long did he spend on his homework?

Step 1: From 5:50 PM to 6:00 PM is 10 minutes.

Step 2: From 6:00 PM to 7:00 PM is 1 hour.

Step 3: From 7:00 PM to 7:10 PM is 10 minutes.

Step 4: Add the time intervals: 10 minutes + 1 hour + 10 minutes = 1 hour and 20 minutes.

Answer: Sipho spent 1 hour and 20 minutes on his homework.

Temperature Understanding Celsius: Temperature is measured in degrees Celsius (°C) in South Africa. A thermometer is used to measure temperature. The liquid inside the thermometer rises or falls depending on how hot or cold it is.

Reading a Thermometer: Look carefully at the scale on the thermometer. Each line represents a degree Celsius. Note the starting number and count how many lines the liquid has risen to find the temperature.

Practical Problems with Temperature: We can use temperature to solve real-world problems, such as comparing temperatures on different days or determining the difference in temperature between two locations.

Example 1: Reading a Thermometer The liquid in a thermometer rises to the 25th line above 0°

C. What is the temperature?

Answer: 25°C Example 2: Temperature Difference The temperature in Johannesburg is 18°C, and the temperature in Cape Town is 26°

C. What is the difference in temperature between the two cities?

Step 1: Subtract the lower temperature from the higher temperature: 26°C - 18°C = 8°C Answer: The difference in temperature is 8°

C. Example 3: Temperature Change The temperature in Durban at 8:00 AM is 20°

C. By 12:00 PM, the temperature has risen by 7°

C. What is the temperature at 12:00 PM?

Step 1: Add the temperature rise to the original temperature: 20°C + 7°C = 27°C Answer: The temperature at 12:00 PM is 27°

C. Everyday Measurement Problems Units of Measurement: Length: We use meters (m) and centimeters (cm) to measure length. 1 meter = 100 centimeters. Sometimes, we also use kilometers (km) for longer distances. 1 kilometer = 1000 meters.

Mass: We use kilograms (kg) and grams (g) to measure mass (how heavy something is). 1 kilogram = 1000 grams.

Capacity (Volume): We use liters (L) and milliliters (ml) to measure capacity (how much a container can hold). 1 liter = 1000 milliliters.

Solving Word Problems: Read the word problem carefully. Identify the units of measurement involved. Decide which operation (addition, subtraction, multiplication, or division) is needed to solve the problem. Write down the calculation and state the answer with the correct unit.

Example 1: Length A piece of rope is 2 meters long. John cuts off 75 centimeters. How much rope is left?

Step 1: Convert meters to centimeters: 2 meters = 2 x 100 = 200 centimeters.

Step 2: Subtract the length that was cut off: 200 cm - 75 cm = 125 cm Answer: There are 125 centimeters of rope left. (You can also say 1 meter and 25 centimetres).

Example 2: Mass A bag of potatoes weighs 5 kg. If Thandi uses 1.5 kg for dinner, how much potatoes are left in the bag?

Step 1: Subtract the mass used from the original mass: 5 kg - 1.5 kg = 3.5 kg Answer: There are 3.5 kg of potatoes left in the bag.

Example 3: Capacity A bottle contains 2 liters of juice. Sipho drinks 350 ml of juice. How much juice is left in the bottle?

Step 1: Convert liters to milliliters: 2 liters = 2 x 1000 = 2000 milliliters.

Step 2: Subtract the amount drunk: 2000 ml - 350 ml = 1650 ml Answer: There are 1650 ml of juice left in the bottle. (You can also say 1 litre and 650 millilitres).