Teacher Preparation

Introduction

In this activity students will observe water droplets forming under the plastic shrink wrap. They will compare two bowls, one with and one without a covering of shrink wrap. Students will explain in their language what they observe. It is important that they use the word evaporation to explain the differences between the bowls.

Activity

Show students a glass bowl. Ask a student to use a measuring cup to pour a measured volume of water into it.

Ask students what will happen to the water in the bowl over the next few days.

Record their ideas.

Take another bowl and ask a student to use the measuring cup to pour exactly the same volume water into it. Ask the student to help cover the bowl in plastic shrink wrap.

Ask students what will happen to the water in the bowl over the next few days.

Record their ideas.

Ask students if they think there will be a difference. How will they know for sure if one or both the bowls have less water?

Observe the bowls the next day. Which of the students ideas match their observations? Can students explain what happened in the two bowls? To help explain the droplets of water under the shrink wrap reflect on what occurs on car windows on cold mornings and in the bathroom on the mirror after a shower. Consider if your students are ready for the term condensation. Did the uncovered bowl lose water? Where did the water go?

How did their original ideas match their observations? Can students make a statement that explains their observation?

Use the diagram below on a smartboard or draw something similar on a whiteboard or blackboard. Ask students to explain the diagram and what the arrows mean. How can they compare the diagram with their experiment?

Extension: A more sophisticated water cycle.

All you need is:

• Glass jar and lid (1)

• Plants (you could use easy to grow sprouts if you like – then you can eat them when they’re big enough) (2)

• Bottle cap or shell of water (3)

• Soil (4)

• Sand (5)

• Small rocks (6)

Directions:

1. Fill the jar as in the picture and put the lid on (small rocks on the bottom, then sand, then soil, and then the plants)

2. Put the jar in a sunny place and see the water cycle work its magic!

Water Cycle Investigation

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Lesson Details

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