Lesson Notes By Weeks and Term v5 - Grade 5

Lesson Video

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Performance objectives

• Calculate elapsed time in hours and minutes.
• Read and interpret temperatures on thermometers.
• Solve word problems involving length, mass, and capacity.
• Estimate and measure using appropriate units.

Lesson summary

This week, we're diving into the world of time, temperature, and measurements – all things we encounter every single day! Understanding these concepts isn’t just about doing well in maths; it's about being able to plan your day, cook a meal safely, build things, and even understand the weather forecast. Imagine planning a braai with your family and not knowing what temperature to set the oven to, or trying to catch a taxi without knowing how long it will take to get to your destination! These are essential skills for navigating daily life in South Africa. We'll be focusing on practical applications and making sure you can solve real-world problems.

Lesson notes

a)

Time: Time is a fundamental concept that helps us organize events and understand duration. We measure time in seconds, minutes, hours, days, weeks, months, and years.

Remember these conversions: 60 seconds = 1 minute 60 minutes = 1 hour 24 hours = 1 day 7 days = 1 week Elapsed Time: Elapsed time is the amount of time that passes between a start time and an end time.

Example 1: Your favourite radio show starts at 14:30 (2:30 PM) and ends at 16:15 (4:15 PM). How long is the show?

Solution: From 14:30 to 15:00 is 30 minutes.

From 15:00 to 16:00 is 1 hour.

From 16:00 to 16:15 is 15 minutes.

Total time: 30 minutes + 1 hour + 15 minutes = 1 hour and 45 minutes. The show is 1 hour and 45 minutes long.

Example 2: A bus leaves Cape Town at 08:45 and arrives in Worcester at 11:

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0. How long was the bus journey?

Solution: From 08:45 to 09:00 is 15 minutes.

From 09:00 to 11:00 is 2 hours.

From 11:00 to 11:20 is 20 minutes.

Total time: 15 minutes + 2 hours + 20 minutes = 2 hours and 35 minutes. The bus journey was 2 hours and 35 minutes long. b)

Temperature: Temperature tells us how hot or cold something is. In South Africa, we use the Celsius scale (°C). A thermometer is used to measure temperature.

Key temperatures to remember: 0°C: Freezing point of water 100°C: Boiling point of water Approximately 37°C: Normal human body temperature Example 1: The temperature in Johannesburg is 28°C during the day and drops to 15°C at night. What is the difference in temperature?

Solution: Difference = 28°C - 15°C = 13°

C. The temperature difference is 13°

C. Example 2: You put a jug of water in the freezer. The water starts at 22°

C. After 3 hours, the water freezes at 0°

C. How much did the temperature drop?

Solution: Temperature drop = 22°C - 0°C = 22°

C. The temperature dropped by 22°C. c)

Everyday Measurement Problems: We use measurements every day to describe the size, weight, and capacity of things.

Length: How long something is (measured in millimetres (mm), centimetres (cm), meters (m), and kilometres (km)).

Remember: 10 mm = 1 cm, 100 cm = 1 m, 1000 m = 1 km.

Mass: How heavy something is (measured in grams (g) and kilograms (kg)).

Remember: 1000 g = 1 kg.

Capacity: How much a container can hold (measured in millilitres (ml) and litres (L)).

Remember: 1000 ml = 1

L. Example 1 (Length): A table is 2 meters long and 80 centimetres wide. What is the perimeter of the table in centimeters?

Solution: Convert meters to centimeters: 2 m = 2 100 cm = 200 cm Perimeter = 2 (Length + Width) = 2 (200 cm + 80 cm) = 2 280 cm = 560 cm. The perimeter of the table is 560 cm.

Example 2 (Mass): You buy 2.5 kg of potatoes and 1.2 kg of onions. What is the total mass of vegetables you bought?

Solution: Total mass = 2.5 kg + 1.2 kg = 3.7 kg. You bought 3.7 kg of vegetables.

Example 3 (Capacity): A bottle contains 1.5 litres of juice. You pour out 750 ml. How much juice is left in the bottle?

Solution: Convert litres to millilitres: 1.5 L = 1.5 1000 ml = 1500 ml Juice left = 1500 ml - 750 ml = 750 ml. There are 750 ml of juice left. Guided Practice (With Solutions)

Question 1: A movie starts at 19:15 (7:15 PM) and ends at 21:30 (9:30 PM). How long is the movie?

Solution: From 19:15 to 20:00 is 45 minutes.

From 20:00 to 21:00 is 1 hour.

From 21:00 to 21:30 is 30 minutes.

Total time: 45 minutes + 1 hour + 30 minutes = 1 hour and 75 minutes = 2 hours and 15 minutes. The movie is 2 hours and 15 minutes long.

Commentary: We broke the problem down into smaller time intervals to make it easier to calculate.

Question 2: The temperature in Durban is 25°

C. The temperature in Kimberley is 11°C lower. What is the temperature in Kimberley?

Solution: Temperature in Kimberley = 25°C - 11°C = 14°

C. The temperature in Kimberley is 14°

C. Commentary: Understanding the phrase "lower than" means subtraction is key.

Question 3: You have a rope that is 3 meters long. You cut off a piece that is 85 cm long. How much rope is left, in centimeters?

Solution: Convert meters to centimeters: 3 m = 3 100 cm = 300 cm Rope left = 300 cm - 85 cm = 215 cm. There is 215 cm of rope left.

Commentary: Make sure the units are the same before subtracting!* Question 4: A container holds 5 litres of water. You pour out 2200 ml. How much water is left in the container in milliliters?

Solution: Convert Litres to milliliters. 5 Litres = 5 x 1000 = 5000ml Water left = 5000ml - 2200ml = 2800ml. There is 2800ml of water left. Independent Practice (Questions Only)

A soccer practice starts at 16:00 and ends at 17:

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5. How long is the practice? The temperature in your house is 22°C. You turn on the heater, and the temperature increases by 5°C. What is the new temperature? A piece of wood is 1.8 meters long. You need to cut it into pieces that are each 30 cm long. How many pieces can you cut? You buy 3 apples, each weighing 150 grams, and a bunch of grapes weighing 250 grams. What is the total weight of the fruit in kilograms? A jug contains 2 litres of water. You pour the water equally into 8 glasses.