DIY: Density Experiment | Tinkerer Box Blog

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Density Experiment

Stem Activities

Ages: 6-8

Less than 30 minutes

Grownup needed

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You may have dropped coins or leaves into water to observe whether they float or sink, but have you tried a liquid density experiment? While the principle is the same and relates to density, watching liquids float is even more magical and visually fascinating. Try this colourful density experiment at home!

Materials Needed

2 cups of water
Food colouring
Salt
Stirring rod
Dropper
Measuring cup

An array of items commonly used in science experiments is arranged on a light woodgrain table against a plain white background. From left to right, there are two clear glasses partially filled with water, a small bottle of blue food coloring, a small glass beaker containing a white powder (possibly baking soda or borax), a clear glass measuring cup with a wooden handle containing a wooden stirring stick and a clear pipette or dropper. This image likely depicts the ingredients and tools gathered before starting a science experiment, possibly making slime.

Step-by-step tutorial

Step 1

Pour salt into one of the cups of water.

A hand pours a white powder from a small glass measuring beaker into a clear glass containing water. The glass sits on a light woodgrain table against a plain white background. The powder is dissolving into the water, creating a cloudy white mixture at the bottom of the glass. This image likely depicts a step in a science experiment or a similar activity where a powder is dissolved in water.

Step 2

Stir thoroughly with the stirring rod until no more salt dissolves.

A clear glass sits on a light woodgrain surface against a plain white background. The glass is partially filled with a cloudy, white liquid, suggesting a substance has been dissolved in the water. This image likely depicts a stage in an experiment or recipe where an ingredient has been mixed into water.

Step 3

Next, add food colouring to the measuring cup.

A hand holds a small bottle of blue food coloring over a clear glass measuring cup with a wooden handle. A drop of blue coloring is falling from the bottle into the cup, where a small puddle of blue liquid has already collected at the bottom. The cup sits on a light woodgrain table against a plain white background. This image likely depicts adding color to a mixture during a science experiment or cooking activity.

Step 4

Using the dropper, add food colouring to both cups and carefully observe the changes that occur.

A hand uses a pipette to drop blue food coloring into two clear glasses of water. A small glass pitcher with a wooden handle, also containing blue liquid, sits next to the glasses on a light wooden table. The food coloring disperses differently in each glass; in one, it forms a distinct layer at the bottom, while in the other, it swirls and mixes more readily. The video likely demonstrates a simple science experiment illustrating concepts like density or diffusion.

Step 5

The food colouring behaves differently in the two cups! Why is this happening?

Two clear glasses partially filled with water and blue coloring sit on a light woodgrain table against a plain white background. In the left glass, the blue coloring has settled in a distinct layer at the bottom. In the right glass, the blue coloring is swirled and dispersed throughout the water, creating a marbled effect. A clear glass measuring cup with a wooden handle containing residual blue coloring sits to the right of the glasses. This image likely illustrates a density experiment or demonstrates the mixing of liquids.

The Science Behind It:

Objects with higher density sink, while those with lower density float. Salt water has a higher density than food colouring, so the colouring floats on top of the salt water. However, since food colouring has a higher density than plain water, it slowly sinks in the cup of plain water.

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