Density Experiment for Kids: why certain objects sink in water!

OctetSci Academy
May 7
2 min read

Updated: 21 hours ago

This colourful density tower experiment is a brilliant way to explore how different materials behave in liquids based on their density. Watch in awe as objects float, sink, and settle at different layers—perfect for classrooms, STEM clubs, or at-home learning.

This experiment visually demonstrates density—how much mass a substance has in a given volume—by layering three immiscible liquids (honey, water, and oil) and dropping various objects into them. The results show how density differences affect whether an object sinks or floats.

Density Experiment PDF manual here:

Students will:

Understand the concept of density.
Observe how immiscible liquids form layers.
Learn why objects float or sink depending on relative densities.
Explore properties like buoyancy and molecular composition.

Check out this fascinating video where we demonstrate the Density Layer Experiment step by step here: Density experiment

Materials Needed

1 transparent jar or cup
Honey (or syrup)
Water (add food colouring for contrast)
Cooking oil
A metal screw
A piece of carrot
A Lego brick
A sponge

Step-by-Step Instructions

Pour honey into the bottom of the jar.
Slowly layer colored water on top using a spoon to prevent mixing.
Gently add cooking oil as the top layer.
Drop each object—metal screw, carrot, Lego, and sponge—into the jar one at a time.
Observe where each object ends up!

Object	Final Position	Why It Happens
Metal Screw	Bottom, in the honey	It is denser than all liquids.
Carrot Piece	On top of the honey	Denser than water, less dense than honey.
Lego Brick	Floats on the water layer	Denser than oil, less dense than water.
Sponge	Floats on the oil layer	Full of air, making it the least dense.

Science Behind the Experiment

Density = Mass ÷ Volume
Denser substances sink beneath less dense ones.
Honey is the densest, followed by water, and then oil (least dense).
Objects settle at the layer where the liquid's density matches theirs.
Buoyancy determines if an object will float based on the upward force from the fluid.

Term	Definition
Density	How tightly packed matter is in a substance.
Buoyancy	The force that allows objects to float in a fluid.
Immiscible	Liquids that do not mix (e.g., oil and water).
Layering	Separation of liquids based on their densities.