Hands-On Water Cycle Activity: Measure Evaporation

Looking for a simple, hands-on way to teach the water cycle? Measuring evaporation is an easy activity that brings the process to life for your students. Perfect for classrooms or homeschools, this experiment makes learning about the water cycle engaging and interactive! You can measure evaporation as a stand-alone activity or as part of a larger exploration of water cycle processes.

Before we dive in: The activity from this post comes from my complete Water Cycle Unit. If you’re an educator planning to teach evaporation and the water cycle, you’ll find printable directions, worksheets, and much more in the Water Cycle Unit (plus you’ll support my blog with your purchase! ❤️)

The Water Cycle: a complete unit study + DIY science projects!

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Materials

Gather the following materials to complete this activity:

Two small see-through jars or cups
Liquid measuring cup (or graduated cylinder)
Water
Food coloring
Permanent marker
Student worksheets & printable directions (available in my Water Cycle Unit!)

Measuring Evaporation: Step-by-Step Directions

The basic idea of this lab is that you will have two jars, one with a lid and one without. You will observe the change in the water level in the two jars over several days due to evaporation. Assist your students as they work through the following steps.

Pre-Lab

Before starting the lab activity, ask your students to make some predictions and explain their reasoning.

Will the jar with the lid:

Loose water?
Gain water?
Remain the same?

Will the jar without a lid:

Loose water?
Gain water?
Remain the same?

Part 1: Set Up

You will need to set up the experiment and then wait several days to collect your results. On the first day, take the following steps:

Use a liquid measuring cup to measure equal amounts of water into two small glass jars.
Put a drop of food coloring in each jar.
Use the marker to mark the water level in each jar.
Leave one jar open. Put a lid on the other jar – this will be your control. Discuss with your classmates and/or instructor the purpose of a control in a science experiment.
Place the jars under a covered area so rain can’t fall into them. Wait several days or weeks. Evaporation may occur very slowly in humid climates.

Part 2: Measure Evaporation

Several days later, complete the experiment:

Once the water level is visibly lower in the open jar, use the graduated cylinder or liquid measuring cup to measure the amount of water in each jar. Record the volume on the student worksheet.
The difference between the two jars is the amount of water that evaporated.
Discuss whether water evaporated from each jar – why or why not?

Post-Lab

Ask your students to reflect on their predictions. Were their predictions correct? Why or why not? Which jar lost water? What caused it to lose water?

What’s Next?

Are your students up for a bigger challenge? Now that you’ve observed evaporation, why not measure some other water cycle processes? Be sure to check out my blog post explaining how to measure stream flow with your students and how to measure snow!

Materials for Teaching Evaporation and the Water Cycle

Save time preparing for this activity! My Water Cycle Unit includes printable directions and worksheets for this activity and two other water cycle activities. Plus flashcards, diagrams, and more. Check it out: