ACTIVITY

Meet Our Plant Protectors

Conduct a simple experiment comparing water runoff from a potted plant (representing a tree) and bare soil, to investigate how trees help prevent flooding and pollution.

Help students understand the role of trees and forests in the water cycle, including their function in reducing runoff, filtering water, and protecting ecosystems against flooding, erosion, and extreme weather.

Before:

  • Print one Student Activity Sheet per group and keep the Support Sheet for teachers handy.
  • Gather: 1 well-rooted potted plant, 1 pot of compost/soil (same fill height), 2 trays/basins, a measuring jug, stopwatch, clipboards/pencils, and a tablet/camera.
  • Label pots (“Plant” and “Soil”) and trays to avoid confusion.
1

Introduction

    • Explain the aim: How do trees reduce flooding and pollution?
    • Recap the water cycle briefly and highlight how roots and soil structure influence infiltration and run-off.
2

Setting Up

    • Place each pot in its own tray to catch run-off.
    • Arrange groups so that all pupils can observe safely and clearly.
3

Prediction

    • Ask students to predict which pot will produce more or faster run-off and why. Record their ideas. The Hypothesis Development method is useful here. 
4

Conducting the Experiment

    • Pour 500 ml of water into each pot at the same time.
    • Start the timer for 2 minutes.
    • Observe infiltration and run-off (pupils may take photos or short videos).
5

Measuring and Observing

    • After 2 minutes, measure the run-off collected in each tray with the jug.
    • Compare the colour and clarity of the run-off (sediment indicates erosion or pollution).
6

Recording Results

    • Students complete the table on the Activity Sheet with volumes, colour notes, and observations.
7

Analysis and Discussion

    • Which pot produced more run-off? Which had muddier water? Why?
    • Relate findings to the role of forests: infiltration, filtration, reduced erosion, and flood prevention.
    • Connect to real-world outcomes such as cleaner rivers, reduced flooding, and healthier communities.

The Educated Guess method can be used for the analysis and discussion.

8

Link to Conservation and Curriculum

  • Relate findings to the Sustainable Development Goals (6, 11, 13, 14, 15).
  • Discuss practical actions such as protecting trees, planting hedgerows, or avoiding soil compaction.
9

Reflection and Assessment

Each student finishes two sentences: “Trees reduce flooding by…” and “We observed pollution as…”

The Round Robin – Writing method can also be used. 

Didactic tips:

  • If you have access to several pots and plants, it is also posisble to let students do the experiment themselves.

Extension (optional)

    • Repeat the test with a mulch or leaf-litter layer on the soil pot.
    • Vary the “rainfall” (e.g. 250 ml vs 750 ml) and discuss storm intensity.
    • Older pupils: calculate the percentage difference in run-off; plot simple bar charts.
GreenComp: Sustainability, water cycle, plant conservation
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Act
THEME:
Nature & biodiversity
TIME: 45 minutes
AGE: 10-12 years, 13-15 years

SUBJECTS:

  • Nature sciences

TOOLS / MATERIALS:

  • Student Activity Sheet (1 per group)
  • Support Sheet: Answers for teacher/facilitator 
  • Clipboards/Pencils 
  • Tablet/Camera to record work
  •  A well rooted pot plant (this represents a tree)
  •  A pot filled to the same height with compost/soil
  •  Two white basins or trays to collect the runoff from the two pots 
  • Measuring jug Stopwatch

METHODS:

RESOURCES: