Scientific Inquiry and the Natural World · 5th Class

Active learning ideas

Sublimation and Deposition

Active learning helps students grasp sublimation and deposition because these processes are invisible without concrete examples. Hands-on exploration with dry ice and cold surfaces makes abstract concepts visible, helping students build accurate mental models of phase changes that are otherwise hard to visualize.

• NCCA Curriculum Specifications
• NCCA: Primary - Materials
• NCCA: Primary - Properties and Characteristics

• 20–40 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Case Study Analysis
• 25 min · Whole Class

Demonstration: Dry Ice Sublimation

Place small pieces of dry ice in a clear container with a warm cloth draped over it to trap fog. Students observe the solid disappearing into gas and measure mass loss over time. Discuss safety rules like gloves and ventilation first.

Explain the process of sublimation using dry ice as an example.

Facilitation Tip

During the Dry Ice Sublimation demonstration, use a balance to show students that the mass decreases as the dry ice sublimes, reinforcing that gas has mass and leaving no liquid behind.

What to look for

Present students with images of dry ice and frost formation. Ask them to write one sentence for each image explaining which phase change is occurring and why.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Activity 02

• Case Study Analysis
• 30 min · Small Groups

Experiment: Frost Formation for Deposition

Chill metal cans in a freezer, then place them in humid air. Students watch water vapour deposit as frost, timing the process and noting conditions like temperature. Compare to regular freezing by touching ice cubes.

Analyze the conditions under which sublimation and deposition occur.

Facilitation Tip

For the Frost Formation experiment, place a metal tray in the freezer overnight so students observe visible frost buildup, making deposition tangible.

What to look for

Pose the question: 'How is sublimation different from evaporation, and how is deposition different from condensation?' Facilitate a class discussion where students use the key vocabulary to explain the differences.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Activity 03

• Case Study Analysis
• 20 min · Pairs

Comparison Chart: Phase Changes

Provide diagrams of melting, evaporation, sublimation, and deposition. In pairs, students fill charts with examples, conditions, and particle sketches, then share one key difference with the class.

Compare sublimation to melting and evaporation.

Facilitation Tip

When creating the Comparison Chart, have students include diagrams with arrows showing the direction of energy transfer for each phase change.

What to look for

On a small card, ask students to draw a simple diagram showing either sublimation or deposition. They should label the states of matter involved and the direction of the phase change.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Activity 04

• Case Study Analysis
• 40 min · Small Groups

Inquiry Stations: Sublimation Hunt

Set stations with mothballs, iodine crystals, and dry ice. Groups predict which sublimes, observe over 10 minutes, and rotate to record evidence. Conclude with a class vote on fastest sublimation.

Explain the process of sublimation using dry ice as an example.

Facilitation Tip

At the Inquiry Stations, provide a simple checklist for students to record observations and predictions before rotating to the next example.

What to look for

Present students with images of dry ice and frost formation. Ask them to write one sentence for each image explaining which phase change is occurring and why.

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

A few notes on teaching this unit

Teach this topic through cycles of observation, prediction, and explanation. Start with surprising demonstrations, like dry ice disappearing without a puddle, to create cognitive conflict. Use small-group discussions to resolve observations into explanations, avoiding overemphasis on memorizing terms. Research shows students learn phase changes best when they connect energy transfer to molecular motion, so guide them to describe what happens to particles during each process.

Successful learning looks like students correctly identifying sublimation and deposition in real-world examples, distinguishing these processes from melting and freezing, and explaining the role of temperature and pressure. They should use accurate vocabulary when describing state changes and connect observations to scientific explanations.

---

Watch Out for These Misconceptions

• During the Demonstration: Dry Ice Sublimation, watch for students who assume a liquid must form. Redirect them by pointing to the balance and asking, 'Where is the liquid? What do you notice about the mass?'.

  In the Demonstration: Dry Ice Sublimation, students will see no liquid form and observe mass decrease. Prompt them to explain what happens to the dry ice particles and how this differs from melting.

• During the Experiment: Frost Formation for Deposition, watch for students who confuse frost with frozen water. Redirect by asking, 'Did the water freeze first? What do we see forming directly from the air?'.

  In the Experiment: Frost Formation for Deposition, students observe frost forming directly from water vapor. Have them compare this to ice forming from liquid water, focusing on the absence of the liquid phase.

• During the Inquiry Stations: Sublimation Hunt, watch for students who say only dry ice sublimes. Redirect by asking, 'What other solids in the room might sublime? How can we test that idea?'.

  In the Inquiry Stations: Sublimation Hunt, students test multiple examples like mothballs and snow. Encourage them to predict which will sublime faster and explain why, using observations from the stations.

---

Methods used in this brief

• Case Study Analysis