Science · Grade 3 · Matter and Its Properties · Term 2

Evaporation and Condensation

Students will explore evaporation and condensation as parts of the water cycle and as reversible changes of state.

• Ontario Curriculum Expectations
• 2-PS1-4

About This Topic

Evaporation and condensation are fundamental processes in the water cycle and examples of reversible changes of state for matter. Evaporation happens when sunlight heats liquid water, turning it into invisible vapor that rises into the air, which explains why a puddle shrinks and disappears on a sunny day. Condensation reverses this by cooling vapor into liquid droplets, forming dew, fog, or clouds.

These concepts fit squarely into the Grade 3 unit on Matter and Its Properties. Students analyze how these changes contribute to the continuous movement of water on Earth and construct models to show condensation. This work builds foundational understanding of physical changes, distinct from chemical ones, and encourages students to connect everyday observations to scientific explanations.

Hands-on investigations make these invisible processes visible and engaging. When students compare evaporation rates of water in different conditions or watch droplets form on a cold surface, they gain direct evidence that strengthens their mental models and makes abstract science feel immediate and relevant.

Key Questions

1. Analyze how evaporation and condensation contribute to the water cycle.
2. Explain why a puddle disappears on a sunny day.
3. Construct a model to demonstrate the process of condensation.

Learning Objectives

• Explain why a puddle disappears on a sunny day by describing the process of evaporation.
• Analyze how evaporation and condensation contribute to the continuous movement of water in the water cycle.
• Construct a simple model that demonstrates the process of condensation.
• Compare the appearance of water vapor and liquid water, identifying them as different states of the same substance.
• Identify everyday examples of evaporation and condensation in their environment.

Before You Start

Properties of Liquids and Gases

Why: Students need to understand that water can exist as a liquid and a gas (water vapor) to comprehend the changes involved in evaporation and condensation.

Heat and Temperature

Why: Understanding that heat causes changes is crucial, as solar energy drives evaporation and cooling causes condensation.

Key Vocabulary

Evaporation	The process where liquid water turns into an invisible gas called water vapor, usually when heated by the sun. This causes puddles to disappear.
Condensation	The process where water vapor in the air cools down and changes back into tiny liquid water droplets. This forms dew, fog, or clouds.
Water Vapor	Water in its gas form. It is invisible and mixes with the air, rising higher as it heats up.
Water Cycle	The continuous journey water takes on Earth, moving from oceans and lakes into the air and back again through evaporation and condensation.

Watch Out for These Misconceptions

Common Misconception

Evaporation only happens when water boils.

What to Teach Instead

Most evaporation occurs at room temperature with gentle heating from the sun. Hands-on dish experiments show water vanishing without boiling, helping students revise ideas through evidence and peer sharing.

Common Misconception

Water disappears forever during evaporation.

What to Teach Instead

Water changes to vapor but does not vanish; it spreads into the air. Tracking mass before and after evaporation demos or cycle models reveals conservation of matter, clarified in group discussions.

Common Misconception

Condensation creates brand new water.

What to Teach Instead

Condensation collects existing vapor into droplets. Observing jar experiments where vapor from known water reforms liquid builds correct models, with students articulating changes during reflections.

Active Learning Ideas

Demonstration: Condensation Jar

Fill a glass jar with hot water and cover it with a cold plate or lid. Students observe droplets forming on the cold surface as vapor condenses. Discuss how this models cloud formation, then wipe and repeat with ice for comparison.

20 min·Whole Class

Progettazione (Reggio Investigation): Evaporation Race

Place equal amounts of water in shallow dishes under different conditions: sun, shade, fan, salt added. Pairs measure and record water levels every 10 minutes over a lesson. Graph results to compare rates.

45 min·Pairs

Model: Mini Water Cycle

Students seal water and soil in a zip-top bag, tape to a sunny window, and draw labels for evaporation and condensation over days. Observe changes and predict what happens next.

30 min·Small Groups

Puddle Tracker

Mark puddles or spills in the schoolyard with chalk after rain. Small groups measure size hourly and note weather factors. Compile class data to explain disappearance.

40 min·Small Groups

Real-World Connections

• Meteorologists study evaporation and condensation to forecast weather. They observe how quickly puddles dry up or how clouds form to predict rain or fog for communities.
• Clothing manufacturers use knowledge of evaporation to design breathable fabrics. These materials allow sweat (liquid water) to evaporate quickly, keeping people dry and comfortable.
• Brewers and bakers observe condensation on pipes or windows in their facilities. This helps them control temperature and humidity, ensuring consistent product quality.

Assessment Ideas

Exit Ticket

Give students a card with a picture of a drying puddle. Ask them to write two sentences explaining what is happening to the water and what it is called. Then, ask them to draw a simple picture of condensation forming on a cold glass.

Discussion Prompt

Ask students: 'Imagine you are a water droplet. Describe your journey from a puddle into the air and back down as rain. What scientific processes are you experiencing?' Listen for their use of evaporation and condensation.

Quick Check

Hold up a clear plastic bag with a small amount of warm water inside, sealed. Place an ice cube on top of the bag. Ask students to observe and record what they see forming inside the bag and on the underside of the plastic, and to label the process they are witnessing.

Frequently Asked Questions

How do you explain evaporation and condensation in grade 3 science?

Start with familiar examples like drying clothes or car windows fogging up. Use simple demos to show liquid to gas and gas to liquid changes. Connect to the water cycle by noting evaporation lifts water to form clouds, then condensation brings it back as rain. Reinforce with drawings and class charts of observations.

What hands-on activities teach evaporation rates?

Set up evaporation stations with water in sun, shade, wind, or with additives like salt. Students measure daily, record in tables, and discuss variables. This reveals patterns like heat speeding evaporation, building data skills and real-world connections to weather.

How can active learning help students understand evaporation and condensation?

Active approaches like jar condensers or dish races let students see and measure changes directly, countering ideas of magic disappearance. Collaborative predictions and data sharing spark discussions that refine understanding. These methods make reversible states tangible, improving retention over lectures alone.

What are common grade 3 misconceptions about the water cycle?

Students often think puddles sink into ground or clouds hold water like buckets. Address with models showing vapor rise and droplet fall. Experiments prove water cycles continuously, with group talks helping peers challenge and correct each other's views effectively.