Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

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Performance objectives

• Estimate and measure length (m, cm, mm)
• Estimate and measure mass (kg, g)
• Estimate and measure capacity (L, mL)
• Solve word problems with measurement
• Convert between different units

Lesson summary

This week, we delve into the fascinating world of measurement! We'll explore how we measure length, mass, and capacity. Understanding measurement is crucial because it helps us in countless everyday situations. For example, knowing how much sugar to add to our pap, how long it takes to walk to the tuck shop, or how much water is needed to fill a bucket for washing. In South Africa, from measuring land for farming to knowing how much petrol to buy for a taxi, measurement is essential.

Lesson notes

Length Length refers to how long something is. We use standard units to measure length, allowing everyone to understand and compare measurements consistently.

Metre (m): A metre is a common unit for measuring longer distances or the height of objects (like a classroom door).

Centimetre (cm): A centimetre is used for measuring smaller objects (like a pencil). There are 100 centimetres in 1 metre (1 m = 100 cm).

Millimetre (mm): A millimetre is used for very small objects (like the width of a fingernail). There are 10 millimetres in 1 centimetre (1 cm = 10 mm).

Therefore, there are 1000 millimetres in 1 metre (1 m = 1000 mm).

Example 1: Imagine a soccer field. It's much easier to measure the length of the field in metres than in centimetres because the numbers would be much bigger and harder to work with.

Example 2: Measuring the length of your maths textbook is best done in centimetres because metres would be too large and give us a number smaller than one. Millimetres, whilst accurate, would result in a much larger number.

Worked example

A table is 2 metres long and 80 centimetres wide. What is the total length of the table in centimetres?

Step 1: Convert metres to centimetres: 2 m 100 cm/m = 200 cm

Step 2: Add the centimetres: 200 cm + 80 cm = 280 cm

Answer: The table is 280 centimetres long.

Mass

Mass tells us how much matter is in an object – how heavy it is.

Kilogram (kg): A kilogram is a standard unit for measuring heavier objects (like a bag of maize meal).

Gram (g): A gram is used for measuring lighter objects (like a slice of bread). There are 1000 grams in 1 kilogram (1 kg = 1000 g).