practicalaction.org/floatinggardenchallenge Briefly explain that this is a challenge put together by an organisation called Practical Action; a charity who work with poor people all over the world, using technology to help them lift themselves out of poverty. practicalaction.org/floatinggardenchallenge

What problems are caused by climate change? What do you see in the photographs? Where do you think it is happening? What are the main problems for people in the photos? Climate change is making both flooding and drought more of a problem throughout the world.

Impacts of changing climates Practical Action works with people living in Bangladesh who experience some of the worst effects of climate change. Floods affect over 1 million people in Bangladesh and last longer each year. Many families lose their crops and the vegetables they were growing to feed their families.

Why does Bangladesh flood?

Tropical storms

The planet is warming The instrumental record goes back to about 1850. A few areas of the globe have not warmed in recent decades, mainly over some parts of the Southern Hemisphere oceans and parts of Antarctica. The rate of surface warming is not smooth; there are lumps and bumps in the record and this rate has slowed in the recent decade. https://www.ncdc.noaa.gov/cag/global/time-series/globe/land_ocean/ytd/12/1880-2018

Global average sea level is rising… Are there other indicators of the warming? Global sea level has risen, based on historical proxy data and tidal gauges that have been adjusted to allow for rising and falling of land and other factors. Global sea levels have risen about 20cm over the past 100 years – a rate of about 2mm a year. This is faster than the rise over any of the last 5000 years (less than 1mm a year), but still slower than the average rise of 5mm a year predicted for the next 80 years. Most of this rise occurs because as the oceans get warmer, their water takes up more space (thermal expansion). Melting glaciers in the Andes, Himalayas, the Rockies and the Alps are increasingly contributing to sea level rise and melting of ice sheets at the periphery of Greenland and Antarctica are increasingly contributing. IPCC (2013) Figure 13.3

Your Challenge The problem: The land where crops used to grow now gets regularly flooded. Your challenge: Design and build a model of a structure that people could grow their crops on even when it floods (and maybe even keep their chickens safe on ) Explain the challenge: you may like to look at the geography of Bangladesh and get students to think about why Bangladesh is more prone to flooding than other countries. It is important that they understand flooding has always been a problem but climate change is making it worse. There are teacher’s notes to support you to prepare and run the challenge, available on the website.

What should you consider? For crops to grow on flooded land they could be planted on a raft like structure, or ‘floating garden’. The top of your model should be fairly flat so you could grow your own crops on top of it. Your model must not be wider or longer than 20 x 30 cm, so it fits in the test “lake”. It is a good idea to stop the children half way through their design and ask them to briefly explain to the rest of the class what they have done, changes they made and why. It si good for them to reflect, and will give any groups that might be struggling some new ideas. The winning group will be the one whose raft holds the most weight before it sinks.

Building materials Free, but finite supply Willow sticks Lolly sticks Thin Plastic straws Sellotape Elastic bands String corks Cost (also finite supply) Sheets of bubble wrap (£2 per sheet) Plastic trays (£4 per tray) Plastic sheeting (£1 per sheet) Water bottles (£3 per bottle) Thick plastic straws (20p each)

What you need to do… Spend 5 minutes on your own thinking about what you would do Talk to your team-mates and agree a design (and a team name) Choose and collect your building materials Build your model Test it at the testing station (me!) Make changes if needs be Competition

How are real floating gardens made? The rafts are approximately 8 metres long and 1 metre wide. They are made up of layers of water hyacinth, bamboo, cow dung and compost. The crops are then grown on the top layer of soil. The garden floats to the top of the water during the rainy season and returns to ground level when the floods subside. For further information on the technical construction of a floating garden and its use in Bangladesh a technical brief is available at practicalaction.org/technical-briefs-schools-agriculture

Making a difference? Many families are benefiting from their floating gardens as they are able to grow vegetables such as okra and leafy vegetables throughout the year. What do you think happens to the ‘raft’ once the crops have been harvested? Do you think floating gardens would work elsewhere in the world? During harvesting, the rafts can be accessed by foot or by raft or boat if the water is very deep. A more detailed case study of Rahima and how her family has benefited from their floating garden is available in impact at www.practicalaction.org/floating-gardens Floating gardens are an excellent example of sustainable farming. The materials used are locally available. The old rafts are used as fertilizer for the next crop. We have also encouraged farmers to keep ducks instead of goats for one simple reason – ducks float!!

Flooding happens in many places and on many scales….