sink and float activity



This activity is designed for 3-6-year-old children. This science activity allows children to explore the concept of sink or float. 

In this activity, children can play, experiment, and discover why objects float and sink in water.


Why Do Objects Sink or Float?

  • Weight: The weight of an object is the measure of gravitational force acting on that object. Heavy objects sink, and lighter objects float
  • Buoyancy: The buoyancy of an object placed in liquid measures the upward force of the liquid acting on that object. When the upward force acting on an object in liquid is greater than the downward force of gravity (or its weight), the object floats, and vice versa. 
  • Density: Objects denser than water will sink, and objects less dense than water will float. 


Benefits of Sink and Float Activity 

This activity enables the child to promote scientific thinking such as to cause and effect, observations, comparison, reasoning, data gathering, experimentation, and evaluation.

  • It helps in language development by introducing various objects that can sink or float.
  • It develops the OCCI: order, concentration, coordination, and independence.
  • It coordinates and controls hand-eye movement.


Material required for sink or float activity

  • A large container filled with water
  • Two containers to sort floating and sinking objects
  • Objects present at home: 
    • ones that float: feather, Lego, bath toy, crayon, ping pong ball, plastic utensil, pencil, etc. 
    • Ones that sink: toy cars, coins, metal spoon, eraser, dry pasta, etc.
    • Towel to wipe spilled water
    • Tweezers


How to introduce sink and float activity to the child?

Bring the activity from the shelf and organize the material needed. Invite the child to perform the activity and differentiate objects that can sink and float in water. Ask them to sort the objects and put them in their respective containers. Demonstrate the activity slowly and carefully so that the child can see and understand each movement.

  1. Fill the container with water.
  2. Using tweezers, take an object from the basket and place one item into the water at a time.
  3. Ask the child, “does it float or sink?”
  4. Let the child observe whether it floats or sinks.
  5. Remove them from the water with the tweezers.
  6. Place the object into the corresponding labeled container.
  7. Repeat the exercise with every object.
  8. Talk about why some objects sank, and others didn’t.
  9. Discuss the weight, size, and material the object is made of and how this influences the floating ability. Let the children relate to the density, buoyancy, and weight of the object.
  10. This sensory experiment encourages children to be curious, observe closely, and notice patterns. 
  11. Clarify the doubts that a child may express.


Watch the video to learn more about the science behind floating and sinking of objects


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Video created by: by Alejandra Jurado

Primary | Sink, and Float (English) | by Alejandra Jurado


  • English
  • primary
  • science