🧪 Density Tower Experiment

Layer liquids · Float or sink · Density science · Grades 2–5

📐 What is Density?
DefinitionDensity = how much stuff (mass) is packed into a space (volume). Dense things feel heavy for their size
ExampleA bowling ball and a beach ball are the same size, but the bowling ball is way denser — more matter packed in
Liquids tooLiquids have different densities too — that's why oil floats on water!
🥞 Build a Density Tower
Layer 1 (bottom)Honey — density ~1.42 g/mL — the densest liquid, sinks to the bottom
Layer 2Corn syrup — density ~1.33 g/mL — slightly less dense than honey
Layer 3Milk — density ~1.03 g/mL — just barely denser than water
Layer 4Water — density 1.00 g/mL — the baseline we compare everything to
Layer 5Vegetable oil — density ~0.92 g/mL — less dense than water, floats on top
Layer 6 (top)Rubbing alcohol — density ~0.79 g/mL — the least dense, floats on everything
🔬 The Science
Why layers?Denser liquids sink below less dense ones — gravity pulls heavier liquids down more
Won't mixSome liquids don't mix (immiscible) because their molecules repel each other — like oil and water
Try itDrop small objects in: a grape sinks to the bottom, a cherry tomato floats on corn syrup, a ping pong ball sits on top!
🎯 Quiz Time!
⭐ 0Q 1/4

Build a Density Tower: Layered Liquids Experiment

A density tower is a stunning visual demonstration of a fundamental physics concept: liquids with different densities naturally separate into layers, with denser liquids sinking to the bottom and less dense liquids floating on top. By carefully pouring honey, corn syrup, dish soap, water, vegetable oil, and rubbing alcohol into a tall glass, students create a rainbow tower of distinct layers that can remain separated for hours.

This interactive guide walks students through building a density tower step by step, explains the science behind each layer, and extends the experiment with objects that float at different levels — demonstrating that density determines not just liquid layering but whether solid objects sink or float.

Why Liquids Layer

Density is mass per unit volume — how much stuff is packed into a given space. Honey is dense because its sugar molecules are tightly packed. Rubbing alcohol is less dense because its molecules are lighter and more spread out. When placed together, gravity pulls denser liquids down and less dense liquids rise, creating the tower. This same principle explains why oil floats on water in ocean spills and why hot air rises above cold air.

Extend the experiment by dropping small objects into the tower: a grape, a cherry tomato, a piece of plastic, a cork. Each object settles at the layer matching its own density, creating a visual "density ruler." Students can predict where each object will float before testing, building scientific reasoning through the hypothesis-test-observe cycle that defines experimental science.

Last reviewed: May 2026 · Aligned with NGSS 2-PS1-1, 5-PS1-3

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