What is the passage mainly about?

Why ice floats and often leaves liquid habitat beneath a lake’s surface (The passage explains the density of ice, then shows how floating ice can protect liquid water below.)

What does a floating sheet of ice do?

It slows heat loss from the water below (The third paragraph says the sheet acts like a lid and slows the loss of heat.)

What would happen first if ice were denser than liquid water?

New ice would sink after it formed (Something denser than the liquid around it sinks, so newly formed ice would drop.)

In this passage, “density” describes

how much mass is packed into an amount of space (The first paragraph defines density as how much mass is packed into each bit of space.)

The Lake’s Winter Lid: Level 2 Reading Comprehension Questions

Drop a stone into water and it sinks. Place an ice cube in water and it floats. The reason is density: ice has less mass packed into each bit of space than liquid water does.

As water freezes, its molecules join in an open pattern with small gaps. The same amount of water takes up more room as ice. Because it is less dense than the liquid around it, the ice stays on top.

This matters in a lake. On a cold day, ice forms at the surface instead of dropping to the bottom. The floating sheet acts like a lid and slows the loss of heat. Water can remain liquid beneath it, giving fish, frogs, and other organisms a winter habitat.

If ice were denser than liquid water, new ice would sink. More water at the surface could then freeze and sink too. A lake might freeze much more deeply. The floating lid does not protect every lake in every condition, but its position at the top often leaves living space below.

Comprehension questions