In this lab, we will examine the water cycle. Review the water cycle in this week’s reading before beginning

Introduction: In this lab, we will examine the water cycle. Review the water cycle in this week’s reading before beginning. Remember, the scientific method involves observations and predictions (hypotheses). Beginning this lab with predictions will help you understand the water cycle better as well as reinforce the scientific method.


  • Two clear zip top bags
  • Water
  • Food coloring
  • Sunny window


Pour a small amount of water in both zip top bags. In one bag, add food coloring. (If you do not have food coloring, use a small amount of a water-based liquid that is already colored like dark or bright juice, sports drink, etc.)

Place both bags in a sunny window (this requires timing as some windows get morning sun, while others may get evening sun). You may need to prop up the bags, but try not to block the sun.

Check the bags periodically (at least 6 times) and describe what you see. Include details about any color changes, water vapor, water droplets, water movement, color of water that accumulates on the bag, etc.

Note: If you do not note any changes. Microwave the bag for 10 second intervals, making observations after each. Do not remove bag from microwave to make observations and let bag cool before removing.

Fill out the following table with your observations, include time of observation to get a sense of time passage between observation:

Observation time Description


Follow-up Questions:

  1. Summarize the progression of what you observed?
  2. What did the drops on the bag eventually do?
  3. Did you see any color in the water droplets that collected on the inside of the bags?
  4. Does that have any implications for whether pollution would move from a source of water like a lake to another location via precipitation?
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