English exercises are all the better for having a real purpose, so why not encourage your key stage 3 pupils to find out about your school's water conservation policy, and to recommend improvements? Environmentally responsible, money-saving, and an excellent English task. Invite your site manager or bursar to your English classroom to talk about what is being done already. Pupils will need to prepare questions, and can find useful background materials at www.wessexwater.co.ukyourbusinessschools_services.html
Next, put together a proposal for managers to consider. Water Conservation in Schools (www.waterintheschool.co.uk) has useful suggestions, and the downloadable School Model should prove inspiring.