Heavy and Light Objects, Kilograms and Grams for Primary 2

Class: Primary 2
Term: Second Term
Week: 9
Age: 7 years
Duration: 40 minutes
Subject: Mathematics
Curriculum Theme: Not separately stated in the scheme
Previous Lesson: Capacity, I. Ordering of Containers Base on Their
Topic: Heavy and Light Objects, Kilograms and Grams
Subject Matter: Heavy and light objects, use of a hand balance, grams, kilograms and suitable units.

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain

• use heavy and light correctly when comparing objects
• identify gram and kilogram as units of weight
• choose a sensible unit for a familiar object
• compare two objects with a hand balance

Affective Domain

• handle classroom objects and balances carefully

Psychomotor Domain

• place objects gently on a hand balance and observe the lower side

Social Domain

• take turns comparing objects and reporting observations

Reference Materials

The following resources were used in planning this lesson:

• 9 Years Basic Education Curriculum.
• Relevant State Unified Scheme of Work.
• An approved Primary School textbook or teaching resource for the subject.

Instructional Materials

The teacher will teach this lesson with the aid of:

• Objects of different capacity: bag
• book
• pencil
• stone
• chalkboard or whiteboard
• topic flash cards
• worksheet

Rationale for the Lesson

This lesson helps pupils understand and use heavy and light objects, kilograms and grams through familiar objects, clear examples and guided practice. It builds a foundation for accurate mathematical thinking in school and daily life.

Prerequisite/Previous Knowledge

Pupils can count familiar objects, follow simple instructions and use basic number language needed for the lesson. The teacher should check this quickly with concrete materials before introducing the new work.

Lesson Content/Board Summary

Heavy and Light Objects, Kilograms and Grams

Meaning of Weight

Weight tells how heavy or light an object is. When comparing two objects, the heavier one has more weight and the lighter one has less weight.

Using a Hand Balance

A hand balance compares the weights of two objects. The movement of the two pans shows which object is heavier or lighter.

1. Place one object in each pan.
2. Wait until the balance settles.
3. The side that goes down holds the heavier object.
4. The side that rises holds the lighter object.
5. If both sides stay level, the objects have equal weight.

Units of Weight

Grams and kilograms are standard units used for weight.

• Gram is written g and is used for light objects, such as a pencil or small packet.
• Kilogram is written kg and is used for heavier objects, such as a bag of rice or a pupil’s body weight.
• 1 kilogram is equal to 1,000 grams. The correct unit is chosen according to the weight of the object being measured.

Worked Comparisons

Objects may be compared directly with a hand balance, while grams and kilograms are used when a measured value is required.

Example 1: A stone makes its balance pan go down while a pencil makes the other pan rise. Which object is heavier?

Solution

The pan holding the stone moves down because the stone has more weight.
Answer: The stone is heavier, while the pencil is lighter.

Example 2: Which units are suitable for measuring a schoolbag and an eraser?

Solution

A schoolbag is relatively heavy, while an eraser is light.
Answer: Measure the schoolbag in kilograms and the eraser in grams.

Weight Is Not Always Shown by Size

A large empty carton may be lighter than a small stone. Objects should be lifted safely or compared with a balance instead of being judged only by size.

Suggested Lesson Video

The teacher may use this short video after the practical activity to reinforce the lesson.

Teaching Methods/Instructional Techniques

Guided Discovery, Demonstration, Question and Answer and Guided Practice.

Instructional Procedures

Step 1: Introduction to Comparing Weight

Time: 4 minutes

Teaching Skill: Set Induction/Questioning

Teacher’s Activity: The teacher lets pupils hold a pencil in one hand and a book in the other and asks which feels heavier.

Pupils’ Activity: Pupils compare the objects and use heavy, light, heavier and lighter correctly.

Learning Point: Weight describes how heavy or light an object is.

Step 2: Concept Development

Time: 5 minutes

Teaching Skill: Explanation/Observation

Teacher’s Activity: The teacher places a book and stone on opposite balance pans and explains that the lower pan holds the heavier object.

Pupils’ Activity: Pupils observe the pan positions and identify the heavier and lighter object.

Learning Point: A hand balance compares two weights.

Step 3: Teacher Demonstration

Time: 5 minutes

Teaching Skill: Demonstration/Modelling

Teacher’s Activity: The teacher organises pairs to compare approved object pairs on the balance and record each result as heavier than or lighter than.

Pupils’ Activity: Pupils operate the balance in turns and check that it settles before deciding.

Learning Point: Objects can be compared systematically by weight.

Step 4: Guided Practical Work

Time: 6 minutes

Teaching Skill: Guided Practice

Teacher’s Activity: The teacher displays a pencil and bag and asks pupils to choose g or kg for each, then explains the suitable unit.

Pupils’ Activity: Pupils write the suitable unit for four familiar objects.

Learning Point: Grams suit light objects; kilograms suit heavier objects.

Step 5: Topic Application

Time: 5 minutes

Teaching Skill: Practical Activity/Problem Solving

Teacher’s Activity: The teacher checks each group’s work with a hand balance, book, pencil, stone and school bag, asks one group to demonstrate and corrects the first observed error.

Pupils’ Activity: Pupils present their result, compare it with another group and make the correction where necessary.

Learning Point: Pupils apply comparing weight with appropriate materials and explain the result.

Step 6: Independent Reinforcement

Time: 5 minutes

Teaching Skill: Independent Practice

Teacher’s Activity: The teacher lists pencil, stone, exercise book and school bag and asks pupils to compare two pairs and choose g or kg for each object.

Pupils’ Activity: Pupils write the heavier object in each pair and select a suitable weight unit.

Learning Point: Pupils compare weights and match familiar objects with grams or kilograms.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates learning by asking the following questions:

1. What does weight tell us?
2. Use the hand balance to identify the heavier of two supplied objects.
3. Name the two units taught in the lesson and write their symbols.
4. Choose the better unit for a pencil and for a bag of rice.
5. What does it mean if a hand balance stays level?

Pupils’ Activity: Pupils answer the topic questions and carry out the required identification, calculation, drawing, measurement or demonstration with the supplied materials.

Learning Point: Pupils demonstrate the stated knowledge and practical skill for comparing weight.

Step 8: Conclusion

Time: 5 minutes

Teaching Skill: Summary/Feedback

Teacher’s Activity: The teacher revisits the central demonstration with a hand balance, book, pencil, stone and school bag, corrects one likely error and asks pupils to state the rule or property learned.

Pupils’ Activity: Pupils state the main rule or property and complete one final oral or practical check.

Learning Point: The defining idea and correct procedure for comparing weight are retained.

Lesson Keywords

• weight – how heavy or light an object is
• heavy – having more weight in a comparison
• light – having less weight in a comparison
• gram – a unit for measuring light objects, written g
• kilogram – a unit for measuring heavier objects, written kg

Differentiation

Support: Use real objects, larger pictures, teacher modelling, paired work and fewer examples at a time. Allow pupils who need help to point, match, count or demonstrate before writing.

Extension: Ask faster pupils to create one additional correct example, explain their method independently or apply the same idea to another familiar situation without moving to a new topic.

Note for teachers using this lesson plan

Check that the hand balance is level before use. Use safe, dry objects and prevent pupils from lifting loads that are too heavy; correct the idea that every larger object must be heavier. Use the suggested video only after the concrete explanation or as a short reinforcement; pause it for questions. Understanding is shown when pupils can complete the evaluation task with the correct language, method and unit where required.