Lesson Notes By Weeks and Term v5 - Grade 5

Lesson Video

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Performance objectives

• Convert between different units of time.
• Solve word problems involving time.
• Read and interpret temperature in Celsius.
• Solve practical problems with length, mass, and capacity.

Lesson summary

This week, we're diving into time, temperature, and everyday measurement problems. These are essential skills you'll use every single day! From planning your day to understanding the weather forecast, and even cooking your favourite meal, time, temperature, and measurements are crucial. In South Africa, understanding these concepts helps us manage our lives effectively, from planning around Eskom's load shedding schedule to knowing what to wear on a hot summer day in Durban or a cold winter morning in the Drakensberg. We also use measurements every day, for example, when buying groceries at Shoprite or Checkers, or helping to build a shack or fence in our communities.

Lesson notes

2.1 Time Conversions Understanding how time units relate to each other is crucial.

Here's a breakdown: 1 minute (min) = 60 seconds (s) 1 hour (hr) = 60 minutes (min) 1 day = 24 hours (hr) 1 week = 7 days 1 month ≈ 30 days (on average, some are 31, February is 28 or 29) 1 year = 12 months = 365 days (366 days in a leap year)

Example 1: How many seconds are there in 3 minutes?

Solution: 1 minute = 60 seconds.

Therefore, 3 minutes = 3 60 seconds = 180 seconds.

Example 2: How many hours are there in 2 days?

Solution: 1 day = 24 hours.

Therefore, 2 days = 2 24 hours = 48 hours.

Example 3: A movie starts at 14:30 (2:30 PM) and ends at 16:45 (4:45 PM). How long is the movie in hours and minutes?

Solution: First, find the difference in hours: 16 - 14 = 2 hours Next, find the difference in minutes: 45 - 30 = 15 minutes Therefore, the movie is 2 hours and 15 minutes long. 2.2 Solving Time Problems We often need to add or subtract time to solve real-world problems. Remember to carry over or borrow when working with minutes and hours.

Example 4: Thando starts her homework at 17:15 (5:15 PM) and works for 1 hour and 30 minutes. What time does she finish her homework?

Solution: Start time: 17:15 Add 1 hour: 17:15 + 1 hour = 18:15 (6:15 PM)

Add 30 minutes: 18:15 + 30 minutes = 18:45 (6:45 PM)

Thando finishes her homework at 18:

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5. Example 5: A bus leaves Cape Town at 08:00 and arrives in George at 14:

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0. How long was the bus journey?

Solution: Arrival time: 14:30 Departure time: 08:00 Subtract the hours: 14 - 8 = 6 hours Subtract the minutes: 30 - 00 = 30 minutes The bus journey was 6 hours and 30 minutes long. 2.3 Temperature (Celsius) In South Africa, we use the Celsius (°C) scale to measure temperature. Here are some important temperatures to remember: 0 °C: Freezing point of water 100 °C: Boiling point of water Average body temperature is around 37°

C. A comfortable room temperature is around 22-25°

C. Example 6: The temperature in Johannesburg is 15 °C in the morning. By midday, it rises by 8 °

C. What is the temperature at midday?

Solution: Morning temperature: 15 °C Temperature rise: 8 °C Midday temperature: 15 °C + 8 °C = 23 °C Example 7: The temperature in Sutherland is -2 °C at night. By the afternoon, it rises to 12 °

C. What is the difference in temperature?

Solution: Afternoon temperature: 12 °C Night temperature: -2 °C Difference: 12 °C - (-2 °C) = 12 °C + 2 °C = 14 °C 2.4 Everyday Measurement Problems (Length, Mass, Capacity) We use different units for length, mass (weight), and capacity (volume).

Length: Millimetres (mm), centimetres (cm), metres (m), kilometres (km) 1 cm = 10 mm 1 m = 100 cm 1 km = 1000 m Mass: Grams (g), kilograms (kg) 1 kg = 1000 g Capacity: Millilitres (ml), litres (l) 1 l = 1000 ml Example 8: A table is 1.5 metres long. How long is it in centimetres?

Solution: 1 metre = 100 centimetres.

Therefore, 1.5 metres = 1.5 100 centimetres = 150 centimetres.

Example 9: A bag of potatoes weighs 2.5 kg. How many grams does it weigh?

Solution: 1 kg = 1000 grams.

Therefore, 2.5 kg = 2.5 1000 grams = 2500 grams.

Example 10: A bottle contains 750 ml of juice. How many litres of juice are in the bottle?

Solution: 1 litre = 1000 ml.

Therefore, 750 ml = 750 / 1000 litres = 0.75 litres. Guided Practice (With Solutions)

Question 1: Sipho starts playing soccer at 10:30 AM and plays for 1 hour and 45 minutes. What time does he finish playing?

Solution: Start time: 10:30 AM Add 1 hour: 10:30 AM + 1 hour = 11:30 AM Add 45 minutes: 11:30 AM + 45 minutes = 12:15 PM Sipho finishes playing at 12:15 P

M. Commentary: We added the hours and minutes separately, ensuring that the total minutes didn't exceed

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0. If they did, we would convert the extra minutes into an hour and add it to the hours.

Question 2: The temperature in Durban is 28°

C. In Johannesburg, it is 12°C cooler. What is the temperature in Johannesburg?

Solution: Durban temperature: 28°C Temperature difference: 12°C Johannesburg temperature: 28°C - 12°C = 16°C The temperature in Johannesburg is 16°

C. Commentary: We subtracted the temperature difference to find the temperature in Johannesburg, as it was stated to be cooler.

Question 3: A piece of wood is 2.4 meters long. It needs to be cut into pieces that are each 30 cm long. How many pieces can be cut?

Solution: Convert the total length to cm: 2.4 m 100 cm/m = 240 cm Divide the total length by the length of each piece: 240 cm / 30 cm/piece = 8 pieces 8 pieces can be cut from the wood.

Commentary: Before dividing, it's crucial to have both measurements in the same units. We converted meters to centimetres to ensure accurate calculation.

Question 4: How many days are there in 5 weeks?

Solution: 1 week = 7 days 5 weeks = 5 7 = 35 days

Commentary: This is a straightforward multiplication problem. Understanding the relationship between weeks and days is essential.

Question 5: A bottle of water contains 1.5 litres. How many millilitres is this?