Objects that float in water

Lesson Plan Presentation

  • Subject: Basic Science
  • Term: Second term
  • Week: Week 5
  • Class: Primary 2

Previous Lesson: The pupils have previous knowledge of identifying different types of animals.

Topic: Objects That Float in Water

Behavioural Objectives: At the end of the lesson, the pupils should be able to:

  1. Identify objects that float in water.
  2. Explain why certain objects float while others sink.

Instructional Materials:

  • Wall charts
  • Pictures
  • Related online video
  • Flash cards

Methods of Teaching:

  • Class discussion
  • Group discussion
  • Asking questions
  • Explanation
  • Role modeling
  • Role delegation

Reference Materials:

  • Scheme of Work
  • Online information
  • Textbooks
  • Workbooks
  • 9 Year Basic Education Curriculum


Objects that float in water typically have a density less than that of water. Some common examples include:

  • Wood
  • Plastic
  • Cork
  • Styrofoam
  • Rubber
  • Ice (solid form of water)
  1. Which of the following objects is most likely to float in water?
    • a) Iron bar
    • b) Wooden plank
    • c) Lead weight
    • d) Aluminum foil
  2. What property determines whether an object will float or sink in water?
    • a) Color
    • b) Shape
    • c) Density
    • d) Temperature
  3. Ice floats in water because its density is __________.
    • a) Greater than water
    • b) Equal to water
    • c) Less than water
    • d) Variable
  4. Why do ships and boats float despite being made of metal?
    • a) Due to their color
    • b) They contain air pockets
    • c) They are heavy
    • d) They are magnetic
  5. What does buoyancy refer to?
    • a) Downward force
    • b) Upward force
    • c) Side-to-side force
    • d) No force
  6. Gases don’t float in water because they are __________.
    • a) More dense than water
    • b) Less dense than water
    • c) Solid
    • d) Magnetic
  7. Which of these materials is least likely to float in water?
    • a) Styrofoam
    • b) Rubber
    • c) Aluminum
    • d) Cork
  8. How does the shape of an object affect its buoyancy?
    • a) It doesn’t affect buoyancy
    • b) Shapes with more surface area float better
    • c) Shapes with less surface area float better
    • d) Shapes have no impact on floating
  9. The main factor determining whether an object floats in water is its __________.
    • a) Mass
    • b) Color
    • c) Size
    • d) Density
  10. Objects that are __________ will generally float in water.
  • a) Denser than water
  • b) Lighter than water
  • c) Heavier than water
  • d) Darker than water
  1. Why do some metals float in water while others sink?
  • a) All metals float
  • b) Metals are not affected by water
  • c) Only heavy metals sink
  • d) Light metals may float due to lower density
  1. Which of the following liquids would cause an object to float if its density is less than that of water?
  • a) Oil
  • b) Mercury
  • c) Vinegar
  • d) Alcohol
  1. Can an object with a density slightly greater than water float?
  • a) Yes
  • b) No
  • c) Only if it’s painted
  • d) Only if it’s shaped like a boat
  1. What happens to the buoyant force as an object is submerged deeper into water?
  • a) Increases
  • b) Decreases
  • c) Remains the same
  • d) Depends on the object’s shape
  1. Why do some objects sink in water?
  • a) They are too colorful
  • b) They are too big
  • c) Their density is greater than water
  • d) They are made of plastic

What makes an object float in water?

  • Objects float in water when their density is less than that of water. This means they weigh less per unit volume than water, allowing them to displace enough water to stay afloat.

2. Why do some objects sink while others float?

  • Objects sink if their density is greater than that of water. Conversely, objects float if their density is less than that of water.

3. Can metals float in water?

  • Most metals sink in water because their density is typically greater than that of water. However, some light metals and alloys, like aluminum or certain types of steel, can float if they are shaped or constructed in a way that reduces their overall density.

4. Why do ships and boats float despite being made of metal?

  • Ships and boats are designed with hollow spaces or compartments that increase their overall volume without significantly increasing their mass, thus reducing their density and allowing them to float.

5. Do all liquids have the same effect on floating objects?

  • No, different liquids have different densities, which affects how objects float in them. For example, objects that float in water might sink in denser liquids like mercury.

6. Why does ice float in water when most solids sink?

  • Ice floats in water because its density is slightly less than that of liquid water. When water freezes into ice, its molecules form a crystalline structure with more space between them, causing ice to be less dense than liquid water.

7. Can gases float in water?

  • Gases are typically less dense than both liquids and solids, so they don’t float in water as solids or liquids do. Instead, gases dissolve in water or form bubbles that rise to the surface.

8. What is buoyancy, and how does it relate to floating objects?

  • Buoyancy is the upward force exerted by a fluid on an object submerged in or floating on it. Objects float when the buoyant force acting on them is equal to or greater than their weight, allowing them to remain at the surface.

9. Can you determine if an object will float by its size alone?

  • No, an object’s size alone does not determine whether it will float. Instead, it’s the relationship between the object’s volume and its mass (density) that determines whether it will float or sink.

10. How can I calculate whether an object will float in water?

  • You can calculate whether an object will float by comparing its density to the density of water. If the object’s density is less than that of water (approximately 1 gram per cubic centimeter), it will float; if it’s greater, it will sink.


Step 1: The class teacher revises the previous topic by asking questions like “What are some examples of animals we learned about last week?”

Step 2: He introduces the new topic by showing pictures of objects floating in water and asking the class, “Have you ever seen objects floating in water? What are some examples?”

Step 3: The class teacher allows the pupils to give their own examples and he corrects them when the needs arise. For example, if a pupil says “rock” floats, the teacher explains why rocks usually sink.

Conclusion: The class teacher wraps up the lesson by summarizing the key points on the board and asking the pupils to copy them into their notebooks. He ensures that the notes are well written and understood by all pupils.

Evaluation: To evaluate understanding, the teacher asks questions like, “Why do some objects float in water while others sink?” and “Can you give examples of objects that float?”

Assignment: Prepare for the next lesson by reading about the topic “Why Do Things Float?” Try to make shorter sentences, using less difficult words to improve readability for grade 2 pupils.

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