The Water (Hydrologic) Cycle: Transpiration

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In this lab, learners grow broad bean (also called fava bean) plants in three EarthBoxes for a few weeks before exposing one to wind (using a fan), another to heat (using a lamp), and the third to nothing (the control). The experiment investigates how different conditions affect the rate of transpiration, defined as the loss of water through the small openings of the plant leaves called stomata. It takes around 17 days to grow the plants, and the experiment itself requires 4-5 days. Included worksheets ask learners to make predictions, collect and graph data, draw their observations, and analyze their data. [Activity is publicly available through a web crawler capture on]

Quick Guide

Preparation Time:
1 to 4 weeks

Learning Time:
1 to 7 days

Estimated Materials Cost:
Over $20 per group of students

Age Range:
Ages 14 - 18

Resource Types:
Activity, Experiment/Lab Activity


Materials List (per group of students)

  • Three EarthBox kits
  • Empty 1-gallon milk container and measuring cup or other graduated measuring device for watering EarthBoxes
  • Small electric fan
  • Microscopes, slides, and cover slips
  • Three packets of broad bean seeds (minimum 96 seeds)
  • Window ledge with 6-8 hours of Eastern or Southern exposure (two grow lights may be substituted)
  • Heat lamp (or halogen light)


  • Life Sciences
    • Diversity of Life
      • Plants
  • Mathematics
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations

Informal Categories

  • Gardening


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Includes alignment to state and/or national standards:

Access Rights:

  • Free access


Source Collection

  • Science After School Consumer's Guide


  • All rights reserved, EarthBox,