冰与物质状态

了解不同形态的冰和物质状态——海水结冰形成海冰（有盐分，相对较薄）；积雪经数百年压实形成冰川冰（淡水，非常厚）；冰山从冰川上断裂后漂浮在海中；知道水以固态（冰）、液态（水）和气态（水蒸气）存在，并且盐会降低水的冰点。

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

学习证据 / Evidence

• 区分海冰（冻结的海水，有盐分，较薄）和冰川冰（压实积雪，淡水，很厚）
• 解释冰山是从冰川上断裂下来的，并且因为冰的密度比液态水小，所以会漂浮在海里
• 描述水的三种状态（固态、液态、气态），并解释盐会降低冰点

• 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

评估问题 / Assessment

{{name}}能否解释海冰和冰川冰之间的区别，并描述水如何在固态、液态和气态之间变化，比如通过一个用盐水和淡水进行的简单冷冻实验来说明？

Can {{name}} explain the difference between sea ice and glacier ice, and describe how water changes between solid, liquid, and gas — maybe by doing a simple freezing experiment with salt and fresh water?