In Hello World issue 11, Pen Holland and Sarah Wyse discuss how educators and students can get closer to the natural world while honing maths and computing skills. Using a Raspberry Pi, you too can join this citizen science collaboration.
Connectedness to nature as measured by the Nature Connection Index is currently the lowest in young people aged 16-24, with everyone aged 8-34 reporting lower connectedness, compared to the 35+ age groups.
Although there is some positive correlation between individuals living in the same households, parents are now less likely to raise their children where they grew up themselves, and as such they may be less knowledgeable about local species. Connecting with nature does not have to mean a trip out into the wilds: urban ecology is increasingly popular in research, and even the most determined of city dwellers is likely to pass a municipal tree or two during their day.
The positive association between connectedness to nature and wellbeing should encourage us all to appreciate and explore our local environments. However, being at one with the natural world doesn’t preclude an abundance of enjoyable science and technology. For example, the authors’ overriding memory of GCSE maths involves triangles – a lot of triangles – combined with frequent musings over how this could possibly ever be useful in the real world. Fast forward 20 years, and we’ve spent more time than we’d like to count surrounded by triangles, chanting ‘SOH CAH TOA’ in the name of ecology.
Calculating the terminal velocity of winged seeds
The Seed Eater project arose from research into how fast winged seeds (samaras) fall, in order to predict how far they might travel across a landscape, and hence understand how quickly populations of invasive trees might spread. In the past, ecologists have measured the terminal velocity of seeds using stopwatches and lasers, but stopwatches are inaccurate, and lasers are expensive.
Timestamped images in which the seed appears tell us the time taken for it to fall through the field of view (A). The distance at which the seed lands from the wall (B) and the viewing angle of the camera (C) are used to calculate distance travelled by the seed while in view. Finally, the speed at which the seed is travelling can be calculated as distance/time.
Enter stage left, Pieter the Seed Eater; a low-cost device fitted with a Raspberry Pi computer and camera that captures a sequence of images, assesses which timestamped images contain a falling seed, and then calculates how far the seed fell, and hence how fast it was travelling.
Pieter the Seed Eater was introduced in issue 10 of Hello World, and if you missed that, you can download a free PDF copy of the magazine from the website.
Pieter the Seed Eater was designed to measure the terminal velocity of pine (Pinus species) seeds from invasive trees in New Zealand, with a particular interest in the variation in falling speeds among seeds from the same cones, between different cones on the same tree, between trees in the same population, and between populations across the landscape. His diet is now expanding to take in a whole range of pine species, but there are many other species of tree around the world that also have winged seeds, in a variety of fascinating shapes.
Introducing teaching resources
To help emphasise the connections between nature and STEM, and because Pieter doesn’t have time to eat all the seeds, we are making cross-curricular resources available to support teaching activities. These range from tree identification and seed collection, through seed dispersal experiments and Seed Eater engineering, to terminal velocity measurements and understanding population spread.
There are several ways to measure tree height, which can be a stimulating discussion and activity. Fire arrows attached to string over high branches, go exploring on Google street view, or use trigonometry, making measurements in a variety of simple or sophisticated ways. Are they all equally accurate? Would they all work on isolated trees and in a dense forest?
These draw on links from elsewhere (for example, the tree identification keys provided by the Natural History Museum, and helicopter seed templates hosted by STEM Learning UK), as well as new material designed specifically for Pieter the Seed Eater, and more general cross-curricular activities related to ecology. In addition, participants can contribute their data to an online database and explore questions about their data using visualisation tools for dispersal equations and population spread.
The teaching resources fall into four main categories:
- Neighbourhood trees
- Dispersal
- Terminal velocity
- Population spread
Each section contains background information, suggested activities for groups and individuals, data recording sheets, and stretch activities for students to carry out in class or at home. The resources are provided as Google slides under a Creative Commons license so that you can edit and adapt them for your own educational needs, with links to the National Curriculum highlighted throughout (thanks to Mary Howell, professional development leader at STEM Learning UK) and interactive graphics hosted online to help understand some of the concepts and equations more easily. Python code for the Seed Eater can be downloaded or written from scratch (or in Scratch!), so that you can set up the device or let students engineer it from first principles. It will need some calibration, but that is all part of the learning experience, and the resources come with some troubleshooting ideas to get started.
How can you join in?
Relevant resources are available here. These are currently aimed at Key Stage 3 (age 11-14) and 4 (14-16), but will be developed and extended as time passes, feedback is incorporated, and new requests are made.
Ultimately, we would like to reach Key Stage 1 to sixth form and beyond, and develop the project into a citizen science collaboration in which people around the world share information about their local trees and seeds with the global community.
We welcome feedback and engagement with the project from anyone who is interested in taking part – get in touch via Twitter or email [email protected]
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