Science · Grade 2

Active learning ideas

Evaporation and Condensation

Active, hands-on experiments let students SEE evaporation and condensation change water's form. When children measure, observe, and debate, they build lasting understanding from concrete evidence rather than abstract explanations.

• Ontario Curriculum Expectations
• 2-ESS2-3

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Hot Seat
• 45 min · Small Groups

Jar Experiment: Temperature and Evaporation

Pour equal water amounts into clear jars: one warm, one cold. Place near a fan or window, mark water levels hourly with dry-erase markers, and measure daily. Groups chart results and explain differences.

Explain where the water goes when a puddle dries up.

Facilitation Tip

During the Jar Experiment, remind students to record the water level at the exact same time each day to ensure consistent measurements.

What to look for

Present students with two identical cups of water, one placed in a sunny window and one in a shaded area. Ask students to predict which cup will have less water after two hours and explain their reasoning, focusing on evaporation.

• Apply
• Analyze
• Evaluate
• Social Awareness
• Self-Awareness

Activity 02

• Hot Seat
• 20 min · Pairs

Mirror Breath: Condensation Close-Up

Students breathe on mirrors or plastic cups, observe droplets form, then wipe and compare warm vs cool breath. Predict outcomes with ice cubes nearby, draw changes, and share in pairs.

Analyze how temperature affects the rate of evaporation.

Facilitation Tip

When students complete the Mirror Breath activity, ask them to compare the size of the condensation spots on a cold mirror versus a warm one.

What to look for

On an index card, ask students to draw a simple picture showing either evaporation or condensation. Below their drawing, they should write one sentence explaining what is happening in their picture.

• Apply
• Analyze
• Evaluate
• Social Awareness
• Self-Awareness

Activity 03

• Hot Seat
• 30 min · Pairs

Puddle Patrol: Outdoor Tracking

Locate schoolyard puddles after rain, measure sizes with rulers, note weather and temperature. Return same spots over days to log changes, photograph evidence, and graph evaporation rates as a class.

Predict what will happen to water vapor when it gets cold.

Facilitation Tip

Set a timer for the Puddle Patrol so students record their observations at regular intervals and notice patterns in puddle size changes.

What to look for

Ask students: 'Imagine you are a scientist studying puddles. What would you observe to understand where the water goes when a puddle dries up? How would you test if the sun makes it dry faster?'

• Apply
• Analyze
• Evaluate
• Social Awareness
• Self-Awareness

Activity 04

• Hot Seat
• 40 min · Small Groups

Bag Terrarium: Cycle Preview

Seal damp soil and plants in clear plastic bags, tape to sunny windows. Watch inside evaporation and condensation daily, label processes, and discuss water recycling.

Explain where the water goes when a puddle dries up.

Facilitation Tip

For the Bag Terrarium, have students predict the terrarium’s inside temperature and compare it to the outside temperature to explain condensation.

What to look for

Present students with two identical cups of water, one placed in a sunny window and one in a shaded area. Ask students to predict which cup will have less water after two hours and explain their reasoning, focusing on evaporation.

• Apply
• Analyze
• Evaluate
• Social Awareness
• Self-Awareness

A few notes on teaching this unit

Teach this topic by alternating between short, focused experiments and guided discussions. Use simple tools like jars, mirrors, and thermometers to make abstract ideas visible. Emphasize observation over explanation, and encourage children to share their discoveries as a class. Research shows that when students manipulate materials and record data, they develop stronger conceptual understanding.

Students will accurately describe evaporation as water gaining heat and turning to vapor, and condensation as vapor cooling to form droplets. They will use evidence from activities to explain real-world examples like sweaty glasses or shrinking puddles.

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Watch Out for These Misconceptions

• During the Puddle Patrol activity, watch for students who believe puddle water disappears forever when it dries. Have them weigh a wet sponge, leave it in sunlight, and weigh it again to show the mass remains constant, just in a new form.

  During the Jar Experiment, ask students to predict what will happen to the water level over time. When the water level drops, guide them to connect the change to evaporation and discuss where the water went.

• During the Jar Experiment, watch for students who think evaporation only happens in direct sunlight. Have them compare water levels in jars placed in different locations and discuss how heat sources vary.

  During the Puddle Patrol activity, ask students to compare the rate of puddle shrinkage in sunny and shaded areas. Use their data to challenge the idea that sunlight is the only cause.

• During the Mirror Breath activity, watch for students who think condensation creates new water from air. Ask them to trace the source of the vapor by blowing on mirrors held at different distances from their mouths.

  During the Mirror Breath activity, have students draw arrows on their breath diagrams to show vapor moving from their lungs to the mirror, reinforcing that condensation comes from existing vapor.

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Methods used in this brief

• Hot Seat