Class 2 — Mathematics
Measurement: Length, Weight, and Capacity
Class 2
- ✓By the end of this lesson students will be able to compare objects based on their length, weight, and capacity.
- ✓By the end of this lesson students will be able to use non-standard units to measure length, weight, and capacity.
- ✓By the end of this lesson students will be able to identify standard units of length (metre), weight (kilogram), and capacity (litre).
- ✓By the end of this lesson students will be able to understand that standard units give the same measurement for everyone.
Key concepts
Length tells us how long or short an object is. We can also use it to compare how tall or short someone or something is. We often compare lengths using words like 'longer', 'shorter', 'taller', 'shorter'.\n\nNon-standard units for measuring length are things like handspan (the distance from your thumb to your little finger when spread out), footspan (the length of your foot), or cubit (the length from your elbow to your fingertip). These units can be different for different people.\n\nStandard unit for length: To get the same measurement every time, we use fixed units called standard units. The standard unit for measuring length is the metre. We often use a measuring tape or a ruler to measure in metres or centimetres.
Weight tells us how heavy or light an object is. We compare weights using words like 'heavier' and 'lighter'.\n\nNon-standard units for measuring weight can be things like blocks, marbles, or stones. We can use a simple balance scale to compare weights by placing objects on each side.\n\nStandard unit for weight: To get the same measurement every time, we use fixed units. The standard unit for measuring weight is the kilogram. We use a weighing machine or a balance scale with fixed weights (like 1 kg, 2 kg) to measure in kilograms.
Capacity tells us how much liquid a container can hold. We compare capacities using words like 'more' and 'less'.\n\nNon-standard units for measuring capacity can be things like cups, mugs, or small jugs. We can pour liquid from one container to another to compare how much they hold.\n\nStandard unit for capacity: To get the same measurement every time, we use fixed units. The standard unit for measuring capacity is the litre. We use measuring jugs marked in litres to measure liquids like milk or water.
Key facts to remember
- 1Length tells us how long or short an object is.
- 2Weight tells us how heavy or light an object is.
- 3Capacity tells us how much liquid a container can hold.
- 4Non-standard units (like handspan, cup) give different measurements for different people.
- 5Standard units (like metre, kilogram, litre) give the same measurement for everyone.
- 6Metre is the standard unit for length.
- 7Kilogram is the standard unit for weight.
- 8Litre is the standard unit for capacity.
Worked examples
Example 1
Observe the two pencils shown below. Which pencil is longer?
Answer
Pencil B is longer.
Always observe the starting and ending points of the objects when comparing length.
Example 2
You have a book and a feather. Which one do you think is heavier?
Answer
The book is heavier.
We can often feel the difference in weight by lifting objects.
Example 3
How many handspans long is your classroom blackboard?
Answer
The blackboard is 10 handspans long (this answer will vary for each student).
Remember that the number of handspans will be different for different people because handspans are non-standard units.
Common mistakes
- ✗Confusing length with height: While related, length usually refers to horizontal extent, and height to vertical extent.
- ✗Thinking that non-standard units (like handspan) will give the same measurement for everyone.
- ✗Not understanding that a 'heavier' object will go down on a balance scale.
- ✗Confusing the terms 'capacity' (how much a container can hold) with 'volume' (the space an object occupies, which is a higher class concept).
Exam tips
- ★Read the question carefully to understand if you need to compare or measure.
- ★When comparing, look for clear differences (e.g., which object extends further, which looks bigger/smaller).
- ★For non-standard units, practice measuring different objects around you to get a better understanding.
- ★Remember the names of the standard units for length, weight, and capacity: metre, kilogram, and litre.
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