Engaging the Student (Entry Task) 

Checking for Understanding (exit ticket)

2 class periods

Part A:

• Predict what might happen to a wet paper towel by the end of the class. (See engagement activity and student questions on Pg. 2 of lesson plan).

Part B: 

• Prepare demo on Pg. 2 of the lesson plan about 5-10 minutes before class.
• Show students the two cups you prepared and ask the questions on page 2 of lesson plan. 

Part A:

• Student Evaporation Activity Sheet

Part B: 

• Student Condensation Activity Sheet 

Optional:

• Student Reading 

View the full lesson plan here:

• Lesson 3-6 Part A: The Water Molecule and Evaporation
• Lesson 3-6 Part B: The Water Molecule and Condensation

Answer Key to Student Activity Sheet:

• Student Evaporation Activity Sheet Answers 
• Student Condensation Activity Sheet Answers 

1. Summary

• Students will help design an experiment to see if adding energy (heating) affects the rate of evaporation.
• Students will look at molecular animations to help explain why the heating water increases the rate of evaporation.
• Students will be introduced to a more detailed model of the water molecule. Students will create 3-D Styrofoam models of water molecules.
• Students investigate the condensation of water vapor on the inside of a plastic cup, then design an experiment to see if cooling water vapor even more affects the rate of condensation.
• Students also relate evaporation and condensation to the water cycle. 

      2.  Objectives:

• Students will be able to identify and control variables to design a test to see if heating water affects the rate of evaporation. Students will be able to explain, on the molecular level, why adding energy increases the rate of evaporation.
• Students will be able to describe on the molecular level how cooling water vapor causes condensation.
• Students will also describe the roles evaporation and condensation play in the water cycle.

Part A:

• Materials for Each Group
• 2 quart-size zip-closing plastic storage bags
• Hot water
• Room-temperature water
• 2 squares of brown paper towel
• 2 droppers
• Materials for each student
• 2 Styrofoam balls (11/2-inch)
• 4 Styrofoam balls (1-inch)
• 2 flat toothpicks
• School glue
• Permanent marker
• Links to images/animations for "Explain"/discussion section of lesson:
• Evaporation animation
• Heating and Evaporation Image
• Models of Water Molecules Animation 

Part B: 

• Materials for Each Group
• 1 short wide-rimmed clear plastic cup
• 1 tall smaller-rimmed clear plastic cup
• Hot water (about 50 °C)
• Magnifier
• Materials for the Demo
• 2 clear plastic cups
• Room-temperature water
• Ice cubes
• Gallon-size zip-closing plastic bag
• Links to images/animations for "Explain"/discussion section of lesson:
• Condensation animation 
• Water Cycle Image
• Evaporation and Condensation animation 

Ask students:

1. Do you think evaporation or condensation could be used to purify water?
2. Write up a quick experimental design for how you could test question #1.