Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

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Performance objectives

• This week, we will dive deeper into the world of measurement! Understanding length, mass, and capacity is crucial for everyday life in South Africa. Imagine you are helping your family prepare a meal – you need to measure the right amount of flour (mass), the correct length of ribbon for a birthday present, or the required amount of water (capacity) for a recipe. From building houses to buying groceries, measurement is everywhere! We will build upon what you learned in previous grades and explore these concepts further. Specifically, this week focuses on using and understanding standard units of measurement within the metric system.
• By the end of this week, you will be able to:
• Objective 1: Accurately measure the length of various objects using centimetres (cm) and metres (m) and convert between these units. (CAPS: Measurement - Length).
• Objective 2: Estimate and measure the mass of various objects using grams (g) and kilograms (kg) and convert between these units. (CAPS: Measurement - Mass).
• Objective 3: Estimate and measure the capacity of different containers using millilitres (ml) and litres (l) and convert between these units. (CAPS: Measurement - Capacity).

Lesson summary

This week, we will dive deeper into the world of measurement! Understanding length, mass, and capacity is crucial for everyday life in South Africa. Imagine you are helping your family prepare a meal – you need to measure the right amount of flour (mass), the correct length of ribbon for a birthday present, or the required amount of water (capacity) for a recipe. From building houses to buying groceries, measurement is everywhere! We will build upon what you learned in previous grades and explore these concepts further. Specifically, this week focuses on using and understanding standard units of measurement within the metric system.

Lesson notes

Let's explore length, mass, and capacity in detail.

Length: Length refers to how long something is. We use standard units like centimetres (cm) and metres (m) to measure length. Think of a small ruler – it's usually 30 cm long. A metre is much longer – about the height of a tall Grade 4 learner or the length of a cricket bat.

Important Relationship: 1 metre (m) = 100 centimetres (cm)

Example 1: Let's say you want to measure the length of your classroom. You could use a metre stick. If the classroom is 8 metres long, that means it's 8 x 100 = 800 centimetres long.

Example 2: If a table is 150 cm long, we can convert this to metres. Since 100 cm = 1m, then 150 cm = 1 m and 50 cm, or 1.5 m.

Mass: Mass refers to how much "stuff" is in an object. We often say "weight," but in science, we use the term "mass" more accurately. We use grams (g) for measuring lighter objects and kilograms (kg) for heavier objects. Think of a small packet of chips – it might weigh about 30g. A bag of potatoes might weigh 5 kg.

Important Relationship: 1 kilogram (kg) = 1000 grams (g)

Example 1: Imagine you're buying sugar for your family. A small bag of sugar might have a mass of 1 kg. That means it contains 1000 grams of sugar.

Example 2: A box of crayons has a mass of 350 g. Converting this to kilograms involves dividing by 1000. 350 g = 0.35 kg.

Capacity: Capacity refers to how much a container can hold. We use millilitres (ml) for smaller amounts and litres (l) for larger amounts. Think of a small bottle of juice – it might hold 250 ml. A large bottle of cooldrink might hold 2 litres.

Important Relationship: 1 litre (l) = 1000 millilitres (ml)

Example 1: You're making juice and the recipe calls for 2 litres of water. That's the same as 2 x 1000 = 2000 millilitres of water.

Example 2: A small container of yogurt has a capacity of 150 ml. Converting this to litres involves dividing by 1000. 150 ml = 0.15 l. Guided Practice (With Solutions) Here are some practice questions to help you understand the concepts.

Question 1: A piece of rope is 3 metres long. How many centimetres long is it?

Solution: We know 1 metre = 100 centimetres. So, 3 metres = 3 x 100 = 300 centimetres.

Commentary: We multiplied the number of metres by 100 because each metre contains 100 centimetres.

Question 2: A bag of apples has a mass of 2 kg. How many grams does it weigh?

Solution: We know 1 kilogram = 1000 grams. So, 2 kilograms = 2 x 1000 = 2000 grams.

Commentary: We multiplied the number of kilograms by 1000 because each kilogram contains 1000 grams.

Question 3: A water bottle holds 1.5 litres of water. How many millilitres does it hold?

Solution: We know 1 litre = 1000 millilitres. So, 1.5 litres = 1.5 x 1000 = 1500 millilitres.

Commentary: We multiplied the number of litres by 1000 because each litre contains 1000 millilitres.

Question 4: Sarah measured the length of her book and found it to be 25 cm. Michael measured the same book and said it was 0.25 m long. Are they both correct? Explain.

Solution: Yes, they are both correct. 25 cm is equal to 0.25 m. Since 100 cm = 1 m, dividing 25 cm by 100 gives 0.25 m.

Commentary: This question tests understanding of conversion between units and reinforces that the same length can be expressed using different units. Independent Practice (Questions Only)

Question 1: A swimming pool is 10 metres long. How long is it in centimetres?

Question 2: A packet of biscuits has a mass of 250 grams. What is its mass in kilograms?

Question 3: A jug contains 3 litres of juice. How many millilitres of juice are in the jug?

Question 4: A table is 1.2 metres long. How long is it in centimetres?

Question 5: A bag of potatoes weighs 5000 grams. What is its mass in kilograms?

Question 6: A bucket contains 7500 ml of water. How many litres of water are in the bucket?

Question 7: Convert 4.5 kg to grams.

Question 8: Convert 650 cm to metres.

Question 9: Thando’s pencil is 18 cm long. Sipho’s pencil is 0.15 m long. Whose pencil is longer? By how much (in cm)?

Question 10: Mom buys 2 litres of milk. She uses 750 ml for baking. How much milk is left (in ml)? How much is left (in litres)?