Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Measure and estimate length (cm, m), mass (g, kg), and capacity (ml, l).
• Solve simple word problems.
• Convert between units (e.g., cm to m).
• Compare and order different measurements.

Lesson summary

This week, we delve into the exciting world of measurement! Measurement is all about finding out how long, how heavy, or how much space something takes up. We use measurements every single day, often without even realizing it. Imagine you're sharing a cool drink with your friends on a hot summer's day. You need to know how much juice each person can get, right? Or think about building a sandcastle on the beach. You need to measure the length and width to make sure it's the perfect size! Understanding measurement helps us to solve problems, build things, cook delicious meals, and understand the world around us.

Lesson notes

Length: Length tells us how long something is. We use different units to measure length, depending on the size of the object.

Centimetre (cm): A centimetre is a small unit of length. Think about the width of your finger – that’s roughly a centimetre! We often use centimetres to measure smaller objects like pencils, books, or crayons.

Metre (m): A metre is a larger unit of length. Imagine the length of a cricket bat – that's about a metre! We use metres to measure bigger objects like the height of a door, the length of a room, or the size of a garden.

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

Example 1: Measuring a Pencil Let's say we want to measure the length of a pencil. We would use a ruler. We line up one end of the pencil with the '0' mark on the ruler. Then we look at where the other end of the pencil reaches on the ruler. Let's say it reaches the 15 cm mark. That means the pencil is 15 cm long.

Example 2: Measuring a Classroom To measure the length of a classroom, we would use a measuring tape. We might find that the classroom is 6 metres long. Since 1 metre is 100 centimetres, the classroom is also 6 x 100 = 600 cm long.

Mass: Mass tells us how heavy something is. We use different units to measure mass, depending on the weight of the object.

Gram (g): A gram is a small unit of mass. Think about a paperclip – it weighs about 1 gram! We use grams to measure light objects like sweets, spices, or a feather.

Kilogram (kg): A kilogram is a larger unit of mass. Imagine a bag of potatoes – it weighs about 1 kilogram! We use kilograms to measure heavier objects like a schoolbag, a person, or a pumpkin.

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

Example 1: Weighing an Apple We can use a kitchen scale to weigh an apple. Let's say the scale shows 200g. That means the apple weighs 200 grams.

Example 2: Weighing a Bag of Sugar A bag of sugar might weigh 1 kg. Since 1 kilogram is 1000 grams, the bag of sugar weighs 1000 grams.

Capacity: Capacity tells us how much liquid a container can hold.

Millilitre (ml): A millilitre is a small unit of capacity. Think about a single drop of water – that's roughly 1 millilitre! We use millilitres to measure small amounts of liquid like medicine, eye drops, or ink.

Litre (l): A litre is a larger unit of capacity. Imagine a bottle of cool drink – it usually holds 1 or 2 litres! We use litres to measure larger amounts of liquid like water, juice, or milk.

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

Example 1: Measuring Medicine A doctor might prescribe 5 ml of medicine for a child. That means the child needs to drink 5 millilitres of the medicine.

Example 2: Measuring a Bottle of Water A bottle of water might contain 500ml. Since 1 litre is 1000 millilitres, the bottle of water contains 500/1000 = 0.5 litres (half a litre). Guided Practice (With Solutions)

Question 1: A table is 150 cm long. How long is the table in metres?

Solution: We know that 1 metre = 100 centimetres. To convert centimetres to metres, we divide by

1

0

0. So, 150 cm = 150 / 100 = 1.5 metres.

Answer: The table is 1.5 metres long.

Question 2: A bag of mealie meal weighs 2.5 kg. How much does it weigh in grams?

Solution: We know that 1 kg = 1000 grams. To convert kilograms to grams, we multiply by

1

0

0

0. So, 2.5 kg = 2.5 x 1000 = 2500 grams.

Answer: The bag of mealie meal weighs 2500 grams.

Question 3: A jug contains 800 ml of juice. How much juice is in the jug in litres?

Solution: We know that 1 litre = 1000 millilitres. To convert millilitres to litres, we divide by

1

0

0

0. So, 800 ml = 800 / 1000 = 0.8 litres.

Answer: The jug contains 0.8 litres of juice.

Question 4: Sarah is 1 metre and 25 centimetres tall. How tall is Sarah in centimetres?

Solution: We know 1 metre = 100 centimetres. Sarah is 1 metre tall, which is 100 cm. She is also 25 cm tall. So, Sarah's total height is 100 cm + 25 cm = 125 cm.

Answer: Sarah is 125 cm tall. Independent Practice (Questions Only) A piece of string is 85 cm long. Jabu cuts off 30 cm. How long is the remaining string in centimetres? A watermelon weighs 3 kg. How much does it weigh in grams? A glass contains 250 ml of milk. How many glasses of milk can you pour from a 1-litre carton? A fence is made of 10 planks. Each plank is 2 metres long. How long is the fence in metres? How long is the fence in centimetres? A recipe calls for 750 ml of water. You only have a measuring cup that measures in litres. How many litres of water do you need? A brick has a mass of 2 kg and a textbook has a mass of 750g. What is the total mass in grams? Order the following lengths from shortest to longest: 50 cm, 1 m, 75 cm, 25 cm A runner runs 5 km. How many metres is that? Sipho filled a bucket with 6 litres of water. He used 2500 ml of the water to wash his car. How much water is left in the bucket, in millilitres?