School › Biodiversity › Ages 10–11
Measuring biodiversity
What biodiversity is, how many species we know, why we depend on them and what threatens them. Then do a fair test: does a wild area have more plant species than a mown lawn?
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Biodiversity is the variety of all life on Earth. Scientists have described about 1.7 million species, most of them insects, and they think there are millions more.[1]
One simple way to measure biodiversity is species richness: the number of different species in an area.[1]
Living things depend on one another, and people depend on biodiversity for clean air, food, drinking water and products such as medicines, clothing and paper.[2]
Threats to biodiversity include habitat loss, invasive species, overconsumption, pollution and climate change. Changing how land is used is one of the biggest causes of loss.[2][1]
The IUCN Red List checks how close species are to extinction. In October 2025 it included 172,620 species, and 48,646 of them were threatened with extinction.[4]
Scientists also track how wildlife populations change. WWF's Living Planet Report 2024 found that the average size of monitored wildlife populations fell by 73% between 1970 and 2020.[5]
Try it: Wild corner or mown lawn: which has more species?
You need
- A hoop or a square frame about 50 cm across (a quadrat)
- A simple plant identification sheet or app
- Recording sheet and pencil
- Gloves
Safety
Teacher checks the area for broken glass, dog mess and other hazards. Wear gloves and long sleeves near brambles and nettles, do not pick or taste anything, and wash your hands afterwards.
What to do
- Write a prediction: which area will have more plant species, the mown lawn or the wild corner?
- Plan a fair test: use the same size of frame and the same number of samples in each area.
- In the mown lawn, put the frame down in 5 different places, without choosing the 'interesting' spots (for example, walk a set number of steps each time).
- In each frame, count how many different kinds of plant you can see. You do not need their names: 'plant A', 'plant B' is fine.
- Repeat with 5 frames in the wild corner.
- Calculate the average number of species per frame for each area and compare.
What happens, and why?
The number of different species in an area is its species richness. Comparing two contrasting areas by sampling both in the same way is how ecologists compare diversity. Using the same frame size and the same number of samples keeps the test fair; more samples make the result more reliable.[1][6]
Play: Help or harm?
Does this help biodiversity or harm it?
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 6–7 · Ages 15–16