I bet you didnt know Water can be

I bet you didn’t know… Water can be harvested from the air in very dry climates Teacher Guide Curriculum Areas Ages States of Matter The Water Cycle 7 -11

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Who were the scientists? 9 scientists from 2 countries the world worked on this project: Hyunho Kim, 1 Sungwoo Yang, 1 Sameer R. Rao, 1 Shankar Narayanan, 1* Eugene A. Kapustin, 2, 3 Hiroyasu Furukawa, 2, 3 Ari S. Umans, 1 Omar M. 2, 3, 4 Evelyn N. Wang 1 Yaghi, 1. Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), USA. 2. Department of Chemistry, Kavli Energy Nano. Science Institute and Berkeley Global Science Institute, University of California–Berkeley, USA. 3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, USA. 4. King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Saudi Arabia. Water harvesting from air with metal-organic frameworks powered by natural sunlight. Science 356, 430– 434 (2017) Why do you think these two countries shared their ideas and think it is important to develop atmospheric water harvesting?

What did the scientists know? One third of the Earth is ‘water stressed’. What impact does this have on plants and animals? Water vapour (gas) is present in the air, even in deserts. The amount changes at different time of day.

What did the scientists do? The scientists built a water harvester box which can collect water vapour (gas) from desert air during the night and turn it into drinkable water. Inside the box is a chemical called a MOF, which is made of organic molecules (carbon, hydrogen) and a metal called zirconium. Water vapour ‘sticks’ to the MOF. To make the ‘best’ water harvester, the scientists: • Compared different types of MOFs • Compared different boxes What do we mean by ‘best’ water harvester?

What did the scientists find out? The scientists managed to harvest 2. 8 litres of water in every kilogramme of MOF each day, in the very dry climate. More water can be harvested by using more MOF or bigger boxes. The scientists are already testing new MOFs.

Quick activity Can you collect water from the air you breathe? Resources mirrors, magnifying glasses

Longer Activity [1] Can we find a material that takes up water and releases it again? Resources Plastic lid/plate, shaving gel, table lamp Water vapour taken up Water vapour released Try this in the classroom and/or watch a time-lapse film to observe how shaving gel changes.

Longer Activity [2] Can we show water vapour from the air condenses to form liquid water? Resources Glass, ice, water Where does the liquid water collect?

What happens inside the box? Water vapour ‘sticks’ to the MOF. Heat from the Sun releases the water vapour. There are so many water vapour molecules trapped in the box that some condense as liquid water on the sides.

What other examples of water vapour condensation do you know?

Longer investigation [3] Which materials hold the most water? The scientists changed the types and the amount of MOF powder to discover how they could increase the amount of water vapour captured. Resources different sponges, bowl/bucket of water, empty bottle or jugs, beakers, measuring cylinders, syringes, etc.

Longer investigation [4] Can you think of ways to reduce the use of fresh water? How much water is collected in a few minutes? How much water would be collected in an hour? In a day? In a week? In a year? Resources Dripping tap, beaker or jug, measuring cylinder if the collecting vessel does not have volume markings.

Questions for further learning How do dry, desert habitats compare with other habitats? Children could research animals and plants that are typical in desert regions and compare with either forests, grasslands, polar regions, or their local environment. If comparing 2 regions, children could list similarities and differences. desert parkland

Questions for further learning Collecting water in Kenya Collecting water in Ethiopia What is the impact on the people who live in water-stressed areas of the world? Practical Action STEM challenges engage children in real world issues. Children may also be interested in I bet you didn’t know… Toilets in the Future May Charge Your Mobile Phone which explains why and how scientists have designed a toilet that flushes without water and plumbing.

Questions for further learning Which countries of the world are most likely to be water stressed? The United Nations website has an interactive map which allows anyone to investigate the proportion of people using safe drinking water in different regions of the world.

Maths links Area of learning Activity Capacity – comparing and measuring volume. Which sponges hold the most water? Dripping tap activity. Multiplication Dripping tap activity.

Writing links Area of learning Activity Persuasive writing Leaflet or poster to persuade people to conserve water. Explanation The Water Cycle or How the water harvester works. Diary (a day in the life of…) A child collecting water in a water stressed country. Poem About water stress

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