Teacher sheet · Ages 10–11 · about 45–50 minutes
Rainforests: layers, soil and water
Lesson page: echoesof.science/school/rainforests/ages-10-11/ · Pupil worksheet: echoesof.science/school/rainforests/ages-10-11/print/
Learning aims
- Locate tropical rainforests and describe their climate.
- Describe the four layers and some adaptations of plants and animals.
- Explain why rainforest soils are poor in nutrients.
- Explain transpiration and plan a fair test with a control.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: why might a forest with so many plants have poor soil? Collect ideas. |
| 10 min | Read the text; draw a labelled cross-section of the layers. |
| 20 min | Set up the transpiration fair test (results next day). |
| 5 min | Which layer? game. |
| 5 min | Quiz. |
Materials for the experiment
- Four clear plastic sandwich bags of the same size
- Twist ties or string
- Two similar leafy plants in pots (or two similar branches of the same bush)
- A sunny place and a shady place
- Kitchen scale or a small measuring spoon
- Paper towels
Safety: An adult chooses safe, non-poisonous plants. Do not pick or pull branches. Keep plastic bags away from faces. Wash hands after handling plants and soil.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Rainforest soil must be very rich. | Most rainforest soils are not very fertile; nutrients are recycled quickly into the plants. |
| All rain over a rainforest comes from the sea. | Much of the rain comes from water given off by the trees. |
| The water in the bag came from the air. | The empty control bag stays dry, so the water came from the leaves. |
Worksheet answers
- Emergent: tallest trees above the canopy, strong sun and wind, small waxy leaves. Canopy: thick roof of treetops 30–50 m up that blocks most light; most animals live here. Understory: shady, with vines, ferns and small trees with large leaves. Forest floor: darkest layer, covered with fallen leaves that rot quickly.
- Fallen leaves rot quickly in the warm, wet conditions and the nutrients are taken up straight away by shallow roots and fungi, so few nutrients stay in the soil.
- Changed: sun or shade. Measured: the water collected in each bag. Kept the same: plant type and size, number of leaves, bags, time. The empty bags are a control that shows the water came from the leaves.
- Trees give off water vapour from their leaves (transpiration); this rises and forms clouds, which start the rainy season.
Quiz answers
- Between which two lines do tropical rainforests grow? The Tropic of Cancer and the Tropic of Capricorn. They grow in the warm tropics around the Equator.[1]
- Why do emergent trees have small, waxy leaves? To lose less water in the strong sun and wind. Emergent trees stick out above the canopy into strong sun and wind.[4]
- Why are most rainforest soils not very fertile? Nutrients from rotting leaves are taken up quickly by roots and fungi. Few nutrients are left stored in the soil.[2]
- What is transpiration? Plants giving off water vapour through their leaves. The water vapour leaves through stomata.[6]
- What increases transpiration? Warm, windy weather. Warmth and wind speed it up; humid air slows it down.[6]
- Where did the clouds that start the Amazon's rainy season come from? Water rising from the forest itself. Satellites traced the water vapour to the trees.[5]
Going further
Compare a rainforest city (Manaus, about 2,300 mm of rain a year) with your own town's yearly rainfall. How many times wetter is it?
Sources used in this lesson
- [1] Mission: Biomes – Tropical rainforest (NASA Earth Observatory (Mission: Biomes)): reliability High
- [2] Rainforest (summary) (Encyclopaedia Britannica): reliability High
- [3] Rain forest (National Geographic Society (Education resource library)): reliability Medium-high
- [4] Rainforest layers (Smithsonian Tropical Research Institute): reliability High
- [5] The Amazon makes its own wet season (NASA Earth Observatory): reliability High
- [6] Evapotranspiration and the water cycle (U.S. Geological Survey (Water Science School)): reliability High
- [7] Transpiration bag (Water cycle for kids) (U.S. Geological Survey (Water Science School)): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/rainforests/sources/
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