Warmth and Ice

Solid ice keeps a shape of its own; when it melts, the same material is liquid water that can flow and take the shape of the lower part of its container.

Lesson 2.5: Changing State—Melting
Key Concepts; Engage, Step 2: Where do you think the energy came from to melt the ice?; Explore, Step 3: How could you set up an experiment to test your method?: Melting changes a solid into liquid. Air and a supporting surface can supply energy to colder ice. The lesson suggests hand contact as a way to warm ice, and recommends similar starting pieces when comparing treatments.

Taking the Shape of the Container
Answer by Tamara, paragraphs on ice and liquids, published 22 October 2007: The explanation contrasts stiff solid ice with flowing liquid water. Gravity draws the water downward while the vessel confines it. This supports pouring meltwater into new wells and later observing solid pieces whose outer shapes come from those wells.

Liquid water flows into the lower part of a container; it does not fill all the available space as a gas would.

Ice keeps its own shape while frozen, but that shape gradually changes as it melts. The material is still water.

Energy transfers from Vince's warmer hand and warmer surroundings toward colder ice, helping it melt. His hand loses energy during contact, so the ice can feel cold while his palm becomes wet.

Lesson 2.5: Changing State—Melting
Key Concepts; Engage, Step 2: Where do you think the energy came from to melt the ice?; Explore, Step 3: How could you set up an experiment to test your method?: Melting changes a solid into liquid. Air and a supporting surface can supply energy to colder ice. The lesson suggests hand contact as a way to warm ice, and recommends similar starting pieces when comparing treatments.

This scene shows brief contact and meltwater, not a timed test of how quickly a hand melts ice.

Warmer air and surfaces can also transfer energy to ice. Touching it is not necessary for melting.

Heat is a transfer of energy, not a visible substance. The visible drops are melted ice.

The handled cube stays separate from the ice used for the wrapped-versus-bare comparison.

A sufficiently thick dry insulating wrap around a closed ice container can slow transfer from warmer surroundings, leaving more ice after the same interval than an otherwise matching bare container.

Activity – Be Cool... with Insulation!
Materials; Procedure, steps 1–3; How does it work?; Safety Suggestions: The activity compares ice inside covered containers with and without insulating material; socks are an example. It calls for approximately equal starting ice. Warmer surroundings supply energy to the ice. Materials from the activity should not be consumed.

The pictured amounts are illustrative, not measured results.

A thick, dry wrap can slow heat transfer to colder ice. It does not make cold or prevent melting forever.

The towel stays outside the closed tub, separate from the meltwater.

After the meltwater is cooled sufficiently in a working freezer, it can become solid ice again; round mould wells give the new solid pieces round outer shapes.

Lesson 2.4: Changing State—Freezing
Key Concepts; Engage, Step 1: Teacher Preparation; Explain, steps 4–5: Water becomes solid ice when cooled sufficiently. A teacher demonstration places a small quantity of water in a freezer overnight and observes it the next day. Freezing expands the water, so an open flexible tray with headroom is appropriate. The source does not promise a universal freezing time.

Taking the Shape of the Container
Answer by Tamara, paragraphs on ice and liquids, published 22 October 2007: The explanation contrasts stiff solid ice with flowing liquid water. Gravity draws the water downward while the vessel confines it. This supports pouring meltwater into new wells and later observing solid pieces whose outer shapes come from those wells.

Pump Up Your Savings with Heat Pumps
How They Work, opening paragraph: Refrigeration uses electrical work to move thermal energy out of the cooled space. Combined with the freezing source, this supports explaining that the freezer removes energy from the water; it does not add a substance called cold.

A freezer removes energy from water; it does not add a substance called cold.

Freezing depends on the water amount, starting temperature and freezer conditions. The next-morning scene does not promise a universal freezing time.

Water expands as it freezes, so the partly filled, freezer-safe mould leaves room below its rims.

The open round wells produce shallow round pieces, not spheres. Freezing changes the water’s form; it does not restore the original square cubes.

This exploratory meltwater and refrozen ice are kept separate from food and drinks.

A useful wrapped-versus-bare comparison changes the wrap while keeping the other important starting conditions alike.

Lesson 2.5: Changing State—Melting
Key Concepts; Engage, Step 2: Where do you think the energy came from to melt the ice?; Explore, Step 3: How could you set up an experiment to test your method?: Melting changes a solid into liquid. Air and a supporting surface can supply energy to colder ice. The lesson suggests hand contact as a way to warm ice, and recommends similar starting pieces when comparing treatments.

Activity – Be Cool... with Insulation!
Materials; Procedure, steps 1–3; How does it work?; Safety Suggestions: The activity compares ice inside covered containers with and without insulating material; socks are an example. It calls for approximately equal starting ice. Warmer surroundings supply energy to the ice. Materials from the activity should not be consumed.

A useful comparison begins with similar ice pieces at the same temperature in matching closed tubs, kept together for the same interval. Only one tub is wrapped.

The illustrations show a qualitative comparison, not a measured experiment or a guarantee that every wrap will perform the same way.