---
title: "Ice & States of Matter"
description: "Understand ice in different forms and states of matter — sea ice forms when ocean water freezes (it's salty and relatively thin), glacial ice forms from compacted snow over centuries (fresh water, ver"
canonical: https://lightmysky.com/learn/science/ice-and-states-of-matter-mt_scbDHJZZHK
source: https://lightmysky.com/learn/science/ice-and-states-of-matter-mt_scbDHJZZHK.md
retrieved: 2026-10-19
---

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# Ice & States of Matter

Understand ice in different forms and states of matter — sea ice forms when ocean water freezes (it's salty and relatively thin), glacial ice forms from compacted snow over centuries (fresh water, very thick), and icebergs break off from glaciers and float in the sea; know that water exists as solid (ice), liquid (water), and gas (water vapour), and that salt lowers the freezing point of water

Subject: Science · Area: Polar Regions · Ages 7 to 9
Page: https://lightmysky.com/learn/science/ice-and-states-of-matter-mt_scbDHJZZHK

## Ready when they can

- Distinguish between sea ice (frozen ocean, salty, thin) and glacial ice (compacted snow, fresh water, thick)
- Explain that icebergs break off from glaciers and float because ice is less dense than liquid water
- Describe the three states of water (solid, liquid, gas) and explain that salt lowers the freezing point

## Lesson: Ice & States of Matter

Water is not always the same. It can be a solid, a liquid, or a gas. Ice is water as a solid. The water you drink is a liquid. And water vapour, a gas you cannot see floating in the air, is water too.

*(drawing: Ice melts into water, and water can turn into vapour, a gas.)*

Not all ice is the same. Sea ice forms when the ocean surface freezes. New sea ice traps salty water, so it is salty and usually thin. Glacial ice is different: snow piles up and packs tight over hundreds of years, so it is fresh water and very thick.

When a chunk of fresh glacier ice cracks off, it becomes an iceberg, and it floats because the same size piece weighs less than liquid water. Salt gets in the way of water freezing, so salty ocean water must get colder than fresh water to freeze.

*(drawing: Glacier ice piles up for so long that it grows far thicker than sea ice.)*

**Tip.** Salt gets in the way of water freezing. That is why salty ocean water has to get colder than fresh water before it turns to ice.

**Recap.** Water can be solid, liquid, or gas. Thin sea ice is frozen ocean water holding salty brine, while thick glacier ice is snow squeezed tight over hundreds of years, and chunks of it become floating icebergs.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Ice & Snow](https://lightmysky.com/learn/science/ice-and-snow-mt_SrmHaJXKrX)

## Opens up

- [Glaciers & Ice Sheets](https://lightmysky.com/learn/science/glaciers-and-ice-sheets-mt_5_kErPeeNu)
- [Why Polar Seasons Are Extreme](https://lightmysky.com/learn/science/why-polar-seasons-are-extreme-mt_f9syMry-0S)
- [Polar Oceans and World Climate](https://lightmysky.com/learn/science/polar-oceans-and-world-climate-mt_g1qgxmlJQ2)